3 files changed, 29 insertions, 8 deletions
diff --git a/src/gui/kernel/qoffscreensurface.cpp b/src/gui/kernel/qoffscreensurface.cpp
index fb1dfd8df5..ed1b8d944a 100644
--- a/src/gui/kernel/qoffscreensurface.cpp
+++ b/src/gui/kernel/qoffscreensurface.cpp
@@ -51,7 +51,7 @@ QT_BEGIN_NAMESPACE
     QOffscreenSurface is intended to be used with QOpenGLContext to allow rendering with OpenGL in
     an arbitrary thread without the need to create a QWindow.
 
-    Even though the surface is renderable, the surface's pixels are not accessible.
+    Even though the surface is typically renderable, the surface's pixels are not accessible.
     QOffscreenSurface should only be used to create OpenGL resources such as textures
     or framebuffer objects.
 
@@ -77,6 +77,11 @@ QT_BEGIN_NAMESPACE
     created}. Passing the format returned from QWindow::requestedFormat() to setFormat()
     may result in an incompatible offscreen surface since the underlying windowing system
     interface may offer a different set of configurations for window and pbuffer surfaces.
+
+    \note Some platforms may utilize a surfaceless context extension (for example
+    EGL_KHR_surfaceless_context) when available. In this case there will be no underlying
+    native surface. For the use cases of QOffscreenSurface (rendering to FBOs, texture
+    upload) this is not a problem.
 */
 class Q_GUI_EXPORT QOffscreenSurfacePrivate : public QObjectPrivate
 {
diff --git a/src/platformsupport/eglconvenience/qeglpbuffer.cpp b/src/platformsupport/eglconvenience/qeglpbuffer.cpp
index 2c6c332ac9..89f06ee3a9 100644
--- a/src/platformsupport/eglconvenience/qeglpbuffer.cpp
+++ b/src/platformsupport/eglconvenience/qeglpbuffer.cpp
@@ -55,6 +55,9 @@ QEGLPbuffer::QEGLPbuffer(EGLDisplay display, const QSurfaceFormat &format, QOffs
     , m_display(display)
     , m_pbuffer(EGL_NO_SURFACE)
 {
+    if (q_hasEglExtension(display, "EGL_KHR_surfaceless_context"))
+        return;
+
     EGLConfig config = q_configFromGLFormat(m_display, m_format, false, EGL_PBUFFER_BIT);
 
     if (config) {
@@ -74,7 +77,8 @@ QEGLPbuffer::QEGLPbuffer(EGLDisplay display, const QSurfaceFormat &format, QOffs
 
 QEGLPbuffer::~QEGLPbuffer()
 {
-    eglDestroySurface(m_display, m_pbuffer);
+    if (m_pbuffer != EGL_NO_SURFACE)
+        eglDestroySurface(m_display, m_pbuffer);
 }
 
 QT_END_NAMESPACE
diff --git a/src/platformsupport/eglconvenience/qeglplatformcontext.cpp b/src/platformsupport/eglconvenience/qeglplatformcontext.cpp
index d7c4fd6764..984abe123f 100644
--- a/src/platformsupport/eglconvenience/qeglplatformcontext.cpp
+++ b/src/platformsupport/eglconvenience/qeglplatformcontext.cpp
@@ -278,7 +278,13 @@ void QEGLPlatformContext::updateFormatFromGL()
     EGLSurface prevSurfaceDraw = eglGetCurrentSurface(EGL_DRAW);
     EGLSurface prevSurfaceRead = eglGetCurrentSurface(EGL_READ);
 
-    EGLSurface tempSurface = createTemporaryOffscreenSurface();
+    // Rely on the surfaceless extension, if available. This is beneficial since we can
+    // avoid creating an extra pbuffer surface which is apparently troublesome with some
+    // drivers (Mesa) when certain attributes are present (multisampling).
+    EGLSurface tempSurface = EGL_NO_SURFACE;
+    if (!q_hasEglExtension(m_eglDisplay, "EGL_KHR_surfaceless_context"))
+        tempSurface = createTemporaryOffscreenSurface();
+
     if (eglMakeCurrent(m_eglDisplay, tempSurface, tempSurface, m_eglContext)) {
         if (m_format.renderableType() == QSurfaceFormat::OpenGL
             || m_format.renderableType() == QSurfaceFormat::OpenGLES) {
@@ -316,8 +322,11 @@ void QEGLPlatformContext::updateFormatFromGL()
             }
         }
         eglMakeCurrent(prevDisplay, prevSurfaceDraw, prevSurfaceRead, prevContext);
+    } else {
+        qWarning("QEGLPlatformContext: Failed to make temporary surface current, format not updated");
     }
-    destroyTemporaryOffscreenSurface(tempSurface);
+    if (tempSurface != EGL_NO_SURFACE)
+        destroyTemporaryOffscreenSurface(tempSurface);
 #endif // QT_NO_OPENGL
 }
 
@@ -354,7 +363,8 @@ bool QEGLPlatformContext::makeCurrent(QPlatformSurface *surface)
             : surface->format().swapInterval();
         if (requestedSwapInterval >= 0 && m_swapInterval != requestedSwapInterval) {
             m_swapInterval = requestedSwapInterval;
-            eglSwapInterval(eglDisplay(), m_swapInterval);
+            if (eglSurface != EGL_NO_SURFACE) // skip if using surfaceless context
+                eglSwapInterval(eglDisplay(), m_swapInterval);
         }
     } else {
         qWarning("QEGLPlatformContext: eglMakeCurrent failed: %x", eglGetError());
@@ -383,9 +393,11 @@ void QEGLPlatformContext::swapBuffers(QPlatformSurface *surface)
 {
     eglBindAPI(m_api);
     EGLSurface eglSurface = eglSurfaceForPlatformSurface(surface);
-    bool ok = eglSwapBuffers(m_eglDisplay, eglSurface);
-    if (!ok)
-        qWarning("QEGLPlatformContext: eglSwapBuffers failed: %x", eglGetError());
+    if (eglSurface != EGL_NO_SURFACE) { // skip if using surfaceless context
+        bool ok = eglSwapBuffers(m_eglDisplay, eglSurface);
+        if (!ok)
+            qWarning("QEGLPlatformContext: eglSwapBuffers failed: %x", eglGetError());
+    }
 }
 
 void (*QEGLPlatformContext::getProcAddress(const QByteArray &procName)) ()