Just wanted to share for the 10 people like me who has with an Nvidia + dual screen setup on ArchLinux (btw) with KDE Plasma desktop that since the new plasma 6 update I can finally use the Wayland session option!
The wayland should work has been around for the last 5 years and 5 years ago it was not even close, then 1 or 2 years ago it started not crashing but multi-screen was not OK (I tried all the kernel and driver parameters).
Now for me and my 5+ years-old setup (probably a lot of legacy plasma settings in my .config) it was finally seamless.
From previous tries I already knew that the desktop feels WAY smoother (true 60 fps everywhere, specially for the video players in web browser).
Feels great so far, discord screen-sharing is not there but can be done from Firefox if needed so OK for me.
I hope this post will be informative for some like me who tried several time over the years and didn’t had much hope.
PS : the cursor has a weirdly strong outline (too shiny to my taste) feels like unintended but not a big problem. I spent 30 mins in the options but couldn’t find anything about that.
I’m not a hardware dev, but I’ve been following this issue for several months. Nvidia on Wayland does not implement implicit GPU synchronization currently for Xwayland. Other vendors do.
This issue is related to how/when the framebuffer from the gpu is handed off to be displayed. Implicit sync isn’t a great solution, it’s just what’s been done for Linux in the past.
Here’s a bit more detail if you’re interested:
I believe this issue is more specific to Wayland because Wayland relies on the DRM, direct rendering manager, to facilitate communication between the graphics driver and Wayland clients (applications). Whereas Xorg kinda just covered everything along the pipeline.
Implicit sync sounds like a bit of hack, where software (I assume the client? Or maybe the drm driver?) implicitly checks for the frame to be finished, rather than being signaled when the frame is ready.
So instead, Nvidia has been arguing for, designing and developing an explicit sync Wayland Protocol (and one for Xorg), which will let the graphics driver explicitly signal when a frame is finished and ready to be displayed. This is how the graphics stack works on Windows.
Right now on Nvidia, Xwayland clients will show previous frames, incomplete/corrupted frames or will fail to update when a new frame is rendered. Here’s the XWayland Merge Request. The issue is much worse on drivers > 535.xx after some optimizations worsened the issue. For now, rolling back can help!
There will be benefits in general with explicit sync, but the major ones will be Xwayland functioning properly for Nvidia users, VRR and apps with inconsistent framerates.
And apparently the plan is to have explicit sync ready for the next major driver version (v555).
From the discussions on Github and Gitlab it seems the work for that to happen is done. The changes in the necessary packages (Xwayland, Mesa?) just need to be merged and the the Nvidia driver 555 needs to be released. It hasn’t been that long since the previous release 550. So I guess it is going to take a bit of waiting still.
It’s the explicit sync protocol.
The TL;DR is basically: everyone else has supported implicit sync for ages, but Nvidia doesn’t. So now everyone is designing an explicit sync Wayland protocol to accommodate for this issue.
It’s explicit sync, look at my other comment for links
