[Webkit-unassigned] [Bug 261653] [GTK] 2.42.0 supports WebGL/2 with compositing disabled?

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=261653

--- Comment #9 from Jim Mason <jmason at ibinx.com> ---
(In reply to Jim Mason from comment #8)
> For me, the call to EGL_CreateContext fails if the attribute is set.  I did
> not dig into what ANGLE is doing internally with the attribute.  Also, I did
> not investigate the failures of setupCurrentTexture, as I supposed it was
> somehow related to the attribute.

To be clear, in the failure mode, EGL_CreateContext returns EGL_NO_CONTEXT; removing the attribute, EGL_CreateContext succeeds, but then the subsequent calls to setupCurrentTexture raise a segmentation fault and crash WebKitWebProcess.

Investigating the crash further, it seems this is not related to the attribute.  It happens on the call to glGetIntegerv(GL_TEXTURE_BINDING_2D, &texture) in GraphicsContextGLTextureMapperANGLENicosia.cpp.  In that file, if I change #include <epoxy/gl.h> to #include <GL/gl.h> to avoid libepoxy, then the crash is gone and glGetIntegerv returns with a good value (a monotonically increasing integer).  libepoxy is normally reliable in my environment, so not sure why it is getting confused here.  In any event, I am fine with patching this locally, but you should be aware, at least in my case (X11/NVIDIA), there is an anomaly.

This leaves the one remaining issue with EGL_CONTEXT_VIRTUALIZATION_GROUP_ANGLE.  I will investigate in ANGLE further, but in the meantime, what failure modes should I observe with this off?  I ran https://registry.khronos.org/webgl/sdk/tests/webgl-conformance-tests.html and even with the virtualization group attribute commented out, I find net fewer conformance test failures with 2.42.0 relative to 2.40.5.

Thanks again for your advice.

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