[platform/virtual] Drop support for vgem and rendernode

Summary:
Instead we depend on the surfaceless platform for which we recently
added support. Thus the plugin does not need to use gbm and udev
anymore. So simplifies a lot.

Test Plan: ctest (prior to breaking change) passes

Reviewers: #kwin

Subscribers: kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D18160

TESTING.md

@@ -10,13 +10,13 @@ The following additional software needs to be installed for running the test sui
 * DMZ-white cursor theme
 * breeze window decoration
 
-# Preparing a run of the test suite
+# Preparing OpenGL
-In case your system does not support the EGL extension EGL_MESA_platform_surfaceless,
+Some of the tests require OpenGL. The test suite is implemented against Mesa and uses the Mesa specific EGL extension
-please load the kernel module "vgem". This is required to provide a virtual OpenGL device.
+EGL_MESA_platform_surfaceless. This extension supports rendering without any real GPU using llvmpipe as software
+emulation. This gives the tests a stable base removing variance introduced by different hardware and drivers.
 
-    sudo modprobe vgem
+Users of non-Mesa drivers (e.g. proprietary NVIDIA driver) need to ensure that Mesa is also installed. If your system
-
+uses libglvnd this should work out of the box, if not you might need to tune LD_LIBRARY_PATH.
-Furthermore the user executing the test suite must be able to read and write to the dri device created by vgem.
 
 # Running the test suite
 The test suite can be run from the build directory. Best is to do:

plugins/platforms/virtual/CMakeLists.txt

@@ -14,10 +14,6 @@ add_library(KWinWaylandVirtualBackend MODULE ${VIRTUAL_SOURCES})
 set_target_properties(KWinWaylandVirtualBackend PROPERTIES LIBRARY_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/bin/org.kde.kwin.waylandbackends/")
 target_link_libraries(KWinWaylandVirtualBackend kwin SceneQPainterBackend SceneOpenGLBackend)
 
-if(HAVE_GBM)
-    target_link_libraries(KWinWaylandVirtualBackend gbm::gbm)
-endif()
-
 install(
     TARGETS
         KWinWaylandVirtualBackend

plugins/platforms/virtual/egl_gbm_backend.cpp

@@ -23,19 +23,12 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "virtual_backend.h"
 #include "options.h"
 #include "screens.h"
-#include "udev.h"
 #include <logging.h>
 // kwin libs
 #include <kwinglplatform.h>
 #include <kwinglutils.h>
 // Qt
 #include <QOpenGLContext>
-// system
-#include <fcntl.h>
-#include <unistd.h>
-#if HAVE_GBM
-#include <gbm.h>
-#endif
 
 namespace KWin
 {
@@ -58,39 +51,6 @@ EglGbmBackend::~EglGbmBackend()
     cleanup();
 }
 
-void EglGbmBackend::initGbmDevice()
-{
-    if (m_backend->drmFd() != -1) {
-        // already initialized
-        return;
-    }
-    QScopedPointer<Udev> udev(new Udev);
-    UdevDevice::Ptr device = udev->virtualGpu();
-    if (!device) {
-        // if we don't have a virtual (vgem) device, try to find a render node
-        qCDebug(KWIN_VIRTUAL) << "No vgem device, looking for a render node";
-        device = udev->renderNode();
-    }
-    if (!device) {
-        qCDebug(KWIN_VIRTUAL) << "Neither a render node, nor a vgem device found";
-        return;
-    }
-    qCDebug(KWIN_VIRTUAL) << "Found a device: " << device->devNode();
-    int fd = open(device->devNode(), O_RDWR | O_CLOEXEC);
-    if (fd == -1) {
-        qCWarning(KWIN_VIRTUAL) << "Failed to open: " << device->devNode();
-        return;
-    }
-    m_backend->setDrmFd(fd);
-#if HAVE_GBM
-    auto gbmDevice = gbm_create_device(fd);
-    if (!gbmDevice) {
-        qCWarning(KWIN_VIRTUAL) << "Failed to open gbm device";
-    }
-    m_backend->setGbmDevice(gbmDevice);
-#endif
-}
-
 bool EglGbmBackend::initializeEgl()
 {
     initClientExtensions();
@@ -102,30 +62,8 @@ bool EglGbmBackend::initializeEgl()
         // first try surfaceless
         if (hasClientExtension(QByteArrayLiteral("EGL_MESA_platform_surfaceless"))) {
             display = eglGetPlatformDisplayEXT(EGL_PLATFORM_SURFACELESS_MESA, EGL_DEFAULT_DISPLAY, nullptr);
-        }
+        } else {
-    }
+            qCWarning(KWIN_VIRTUAL) << "Extension EGL_MESA_platform_surfaceless not available";
-    if (display == EGL_NO_DISPLAY) {
-        qCDebug(KWIN_VIRTUAL) << "Failed to create surfaceless platform, trying with vgem device";
-        const bool hasMesaGBM = hasClientExtension(QByteArrayLiteral("EGL_MESA_platform_gbm"));
-        const bool hasKHRGBM = hasClientExtension(QByteArrayLiteral("EGL_KHR_platform_gbm"));
-        const GLenum platform = hasMesaGBM ? EGL_PLATFORM_GBM_MESA : EGL_PLATFORM_GBM_KHR;
-
-        if (!hasClientExtension(QByteArrayLiteral("EGL_EXT_platform_base")) ||
-                (!hasMesaGBM && !hasKHRGBM)) {
-            setFailed("missing one or more extensions between EGL_EXT_platform_base,  EGL_MESA_platform_gbm, EGL_KHR_platform_gbm");
-            return false;
-        }
-
-#if HAVE_GBM
-        initGbmDevice();
-        if (auto device = m_backend->gbmDevice()) {
-            display = eglGetPlatformDisplayEXT(platform, device, nullptr);
-        }
-#endif
-
-        if (display == EGL_NO_DISPLAY) {
-            qCWarning(KWIN_VIRTUAL) << "Failed to create EGLDisplay through GBM device, trying with default device";
-            display = eglGetPlatformDisplayEXT(platform, EGL_DEFAULT_DISPLAY, nullptr);
         }
     }
 

plugins/platforms/virtual/egl_gbm_backend.h

@@ -49,7 +49,6 @@ private:
     bool initializeEgl();
     bool initBufferConfigs();
     bool initRenderingContext();
-    void initGbmDevice();
     VirtualBackend *m_backend;
     GLTexture *m_backBuffer = nullptr;
     GLRenderTarget *m_fbo = nullptr;

plugins/platforms/virtual/virtual_backend.cpp

@@ -31,9 +31,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <fcntl.h>
 #include <unistd.h>
 #include <config-kwin.h>
-#if HAVE_GBM
-#include <gbm.h>
-#endif
 
 namespace KWin
 {
@@ -56,14 +53,6 @@ VirtualBackend::VirtualBackend(QObject *parent)
 
 VirtualBackend::~VirtualBackend()
 {
-#if HAVE_GBM
-    if (m_gbmDevice) {
-        gbm_device_destroy(m_gbmDevice);
-    }
-#endif
-    if (m_drmFd != -1) {
-        close(m_drmFd);
-    }
 }
 
 void VirtualBackend::init()

plugins/platforms/virtual/virtual_backend.h

@@ -28,8 +28,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 class QTemporaryDir;
 
-struct gbm_device;
-
 namespace KWin
 {
 class VirtualOutput;
@@ -59,20 +57,6 @@ public:
     Outputs outputs() const override;
     Outputs enabledOutputs() const override;
 
-    int drmFd() const {
-        return m_drmFd;
-    }
-    void setDrmFd(int fd) {
-        m_drmFd = fd;
-    }
-
-    gbm_device *gbmDevice() const {
-        return m_gbmDevice;
-    }
-    void setGbmDevice(gbm_device *device) {
-        m_gbmDevice = device;
-    }
-
     QVector<CompositingType> supportedCompositors() const override {
         return QVector<CompositingType>{OpenGLCompositing, QPainterCompositing};
     }
@@ -85,8 +69,6 @@ private:
     QVector<VirtualOutput*> m_enabledOutputs;
 
     QScopedPointer<QTemporaryDir> m_screenshotDir;
-    int m_drmFd = -1;
-    gbm_device *m_gbmDevice = nullptr;
 };
 
 }

udev.cpp

@@ -156,36 +156,6 @@ UdevDevice::Ptr Udev::primaryGpu()
     });
 }
 
-UdevDevice::Ptr Udev::virtualGpu()
-{
-    if (!m_udev) {
-        return UdevDevice::Ptr();
-    }
-    UdevEnumerate enumerate(this);
-    enumerate.addMatch(UdevEnumerate::Match::SubSystem, "drm");
-    enumerate.addMatch(UdevEnumerate::Match::SysName, "card[0-9]*");
-    enumerate.scan();
-    return enumerate.find([](const UdevDevice::Ptr &device) {
-        const QByteArray deviceName(udev_device_get_syspath(*device));
-        return deviceName.contains("virtual");
-    });
-}
-
-UdevDevice::Ptr Udev::renderNode()
-{
-    if (!m_udev) {
-        return UdevDevice::Ptr();
-    }
-    UdevEnumerate enumerate(this);
-    enumerate.addMatch(UdevEnumerate::Match::SubSystem, "drm");
-    enumerate.addMatch(UdevEnumerate::Match::SysName, "renderD[0-9]*");
-    enumerate.scan();
-    return enumerate.find([](const UdevDevice::Ptr &device) {
-        Q_UNUSED(device)
-        return true;
-    });
-}
-
 UdevDevice::Ptr Udev::primaryFramebuffer()
 {
     if (!m_udev) {

udev.h

@@ -83,8 +83,6 @@ public:
     }
     UdevDevice::Ptr primaryGpu();
     UdevDevice::Ptr primaryFramebuffer();
-    UdevDevice::Ptr virtualGpu();
-    UdevDevice::Ptr renderNode();
     UdevDevice::Ptr deviceFromSyspath(const char *syspath);
     UdevMonitor *monitor();
     operator udev*() const {