glfw error with explicit synchronization on sway

[krakow10]

Describe the bug
Kitty fails to launch when the sway compositor is using explicit synchronization.

[quat@quat-desktop ~]$ kitty --config NONE
wp_linux_drm_syncobj_surface_v1#40: error 4: Buffer attached but no acquire point set
[0.159] The output buffer does not support sRGB color encoding, colors will be incorrect.
[0.170] [glfw error 65544]: Wayland: fatal display error: Protocol error

To Reproduce
Steps to reproduce the behavior:

1. Use Arch Linux
2. Install sway-git
3. Install NVIDIA driver version 560.35.03
4. Launch kitty
5. See error

Screenshots

[ionenwks]

Haven't tried it but note that issue may possibly be still in egl-wayland (need >=1.1.14 to use explicit sync), egl-wayland-1.1.14 is particularly broken, and 1.1.15 still has issues that crash applications (one major issue was fixed, but no new release yet). Alternatively, it could be wlroots' rather new explicit sync implementation that needs work (Edit: one could try with plasma6/kwin instead to see it happens on both).

Note that nvidia official drivers (current latest 560.35.03) still ship egl-wayland-1.1.13.1 and distros giving an higher version are essentially opting in an early experiment (In Gentoo we're currently leaving it as a opt-in, users don't get 1.1.15 by default). Arch seems to have downgraded back to 1.1.13.1 too, have you gotten that update yet or is it somehow failing even with 1.1.13.1? (if the latter, may indicate it's trying to use explicit sync when it can't).

Not to say bundled glfw may not have something that needs fixing too if it's misusing something and causing unexpected issues.

[kovidgoyal]

Explicit sync is something that happens in lower layers than application
code. If its crashing then the bug is probably in either mesa or the
NVIDIA driver or the compositor. An OpenGL application like kitty just
calls eglSwapBuffers() there is no concept of implicit/explicit
synchronization in this API. So I dont see that anything can be done in
kitty about this. If anybody knows any different feel free to enlighten
me.

[krakow10]

Haven't tried it but note that issue may possibly be still in egl-wayland (need >=1.1.14 to use explicit sync), egl-wayland-1.1.14 is particularly broken, and 1.1.15 still has issues that crash applications (one major issue was fixed, but no new release yet).

egl-wayland is poignant, this was tested with egl-wayland 1.1.15. I found that screen capture doesn't work on any other version but I may have not tested correctly. I may try 1.1.13.1 when I have time.

Edit: The release notes for egl-wayland 1.1.13.1 state that it disables explicit sync, so it is not a valid explicit sync testing target. "...users may want to fall back to 1.1.13 to avoid using explicit sync, but cannot on 560. This release provides an option to fall back to."

[mahkoh]

You must not call wl_surface_attach on a surface that has an egl context.

[kovidgoyal]

On Mon, Aug 26, 2024 at 01:52:39AM -0700, mahkoh wrote: You must not call wl_surface_attach on a surface that has an egl context.

Is this documented somewhere? Where in the Wayland spec does it say that's not allowed? All Wayland compositors have, to date, been fine with this. And I can find no mention of such a restriction in the docs of wl_surface_attach.

[kovidgoyal]

Note, I don't know if the fix actually works, but its the only instance in the codebase I can find of a buffer being attached to a surface that already has an OpenGL context. @krakow10 please test.

[mahkoh]

Is this documented somewhere? Where in the Wayland spec does it say×that's not allowed? All Wayland compositors have, to date, been fine with this.

Insofar that vulkan says

The native window referred to by pCreateInfo->surface must not become associated with a non-Vulkan graphics API surface before all associated Vulkan swapchains have been destroyed.

And similar for opengl. What exactly this means is not necessarily documented.

[krakow10]

Assuming the AUR package installed correctly (installed as kitty-git-1:0.36.1.r16.g9843b5c21-1) I am getting the same error as before.

[kovidgoyal]

Run with --debug-rendering that will tell us the sequence of events. And you can use the kitty nightly build no need to rely on AUR. https://sw.kovidgoyal.net/kitty/build/