Subject: Disable GPU when using nouveau or running on wayland
From: Antonio Larrosa <[email-masked]>

Qt WebEngine uses multi-threaded OpenGL, which nouveau does not support.
It also crashes when running on wayland, the cause is not yet known.
Work around these issues by not doing GPU-accelerated rendering in such
cases.

Index: qtwebengine-everywhere-src-5.12.0-alpha/src/core/web_engine_context.cpp
===================================================================
--- qtwebengine-everywhere-src-5.12.0-alpha.orig/src/core/web_engine_context.cpp
+++ qtwebengine-everywhere-src-5.12.0-alpha/src/core/web_engine_context.cpp
@@ -101,6 +101,7 @@
 #include <QOffscreenSurface>
 #ifndef QT_NO_OPENGL
 # include <QOpenGLContext>
+# include <QOpenGLFunctions>
 #endif
 #include <QQuickWindow>
 #include <QStringList>
@@ -162,6 +163,39 @@ void dummyGetPluginCallback(const std::v
 }
 #endif
 
+#ifndef QT_NO_OPENGL
+QString openGLVendor()
+{
+    QString vendor;
+
+    QOpenGLContext *oldContext = QOpenGLContext::currentContext();
+    QSurface *oldSurface = 0;
+    if (oldContext)
+        oldSurface = oldContext->surface();
+
+    QScopedPointer<QOffscreenSurface> surface( new QOffscreenSurface );
+    surface->create();
+    QOpenGLContext context;
+    if (!context.create()) {
+        qDebug() << "Error creating openGL context";
+    }
+    else if (!context.makeCurrent(surface.data())) {
+        qDebug() << "Error making openGL context current context";
+    } else {
+        const GLubyte *p;
+        QOpenGLFunctions *f = context.functions();
+        if ((p = f->glGetString(GL_VENDOR)))
+            vendor = QString::fromLatin1(reinterpret_cast<const char *>(p));
+    }
+
+    context.doneCurrent();
+    if (oldContext && oldSurface)
+        oldContext->makeCurrent(oldSurface);
+
+    return vendor;
+}
+#endif
+
 } // namespace
 
 namespace QtWebEngineCore {
@@ -440,6 +474,27 @@ WebEngineContext::WebEngineContext()
     const char *glType = 0;
 #ifndef QT_NO_OPENGL
 
+    bool disableGpu = qEnvironmentVariableIsSet("QT_WEBENGINE_DISABLE_GPU");
+
+    if (!qEnvironmentVariableIsSet("QT_WEBENGINE_DISABLE_WAYLAND_WORKAROUND") && qApp->platformName().startsWith("wayland", Qt::CaseInsensitive))
+    {
+        qWarning() << "Running on wayland. Qt WebEngine will disable usage of the GPU.\n"
+                      "Note: you can set the QT_WEBENGINE_DISABLE_WAYLAND_WORKAROUND\n"
+                      "environment variable before running this application, but this is \n"
+                      "not recommended since this usually causes applications to crash.";
+        disableGpu = true;
+    }
+
+    if (!qEnvironmentVariableIsSet("QT_WEBENGINE_DISABLE_NOUVEAU_WORKAROUND") && openGLVendor() == QStringLiteral("nouveau"))
+    {
+        qWarning() << "Nouveau openGL driver detected. Qt WebEngine will disable usage of the GPU.\n"
+                      "Note: you can set the QT_WEBENGINE_DISABLE_NOUVEAU_WORKAROUND\n"
+                      "environment variable before running this application, but this is \n"
+                      "not recommended since this usually causes applications to crash as\n"
+                      "Nouveau openGL drivers don't support multithreaded rendering";
+        disableGpu = true;
+    }
+
     bool tryGL =
             !usingANGLE()
             && (!usingSoftwareDynamicGL()
@@ -450,7 +505,7 @@ WebEngineContext::WebEngineContext()
                 || enableWebGLSoftwareRendering
 #endif
                 )
-            && !usingQtQuick2DRenderer();
+            && !usingQtQuick2DRenderer() && !disableGpu;
 
     if (tryGL) {
         if (qt_gl_global_share_context() && qt_gl_global_share_context()->isValid()) {