Qt on EGLFS without window manager

[HolgerS]

Hi,

I have an x86-based platform on which I would like to run Qt applications on EGLFS directly with DRM, i.e. without a window manager like Wayland or Xorg. For this, I compiled Mesa with platform drm and the necessary drivers. My Qt compile configuration is attached at the bottom of this post.

When trying to run a Qt application, I get the following error:

EGL error : Could not create the egl surface: error = 0x300b

The error 0x300b means EGL_BAD_NATIVE_WINDOW.

I digged into Qt's and Mesa's source code and found the following: The error is raised in Mesa's implementation of eglCreateWindowSurface(). This function is called in Qt's method QEglFSWindow::resetSurface(), as follows:

    ...
    m_window = qt_egl_device_integration()->createNativeWindow(this, surfaceSize, m_format);
    m_surface = eglCreateWindowSurface(display, m_config, m_window, NULL);
    ...

I found out that m_window is always NULL (makes sense, because we don't have a window manager), which is what Mesa does not like, see Mesa's function _eglCreateWindowSurfaceCommon():

static EGLSurface
_eglCreateWindowSurfaceCommon(_EGLDisplay *disp, EGLConfig config,
                              void *native_window, const EGLint *attrib_list)
{
   ...
   if (native_window == NULL)
      RETURN_EGL_ERROR(disp, EGL_BAD_NATIVE_WINDOW, EGL_NO_SURFACE);
   ...

How can I configure Qt in such a way that Mesa is happy?

My Qt configuration is as follows:

Configure summary:

Building on: linux-g++ (x86_64, CPU features: mmx sse sse2)
Building for: devices/linux-ks-sdk-g++ (x86_64, CPU features: mmx sse sse2)
Target compiler: gcc 7.4.0
Configuration: cross_compile sse2 aesni sse3 ssse3 sse4_1 sse4_2 avx avx2 avx512f avx512bw avx512cd avx512dq avx512er avx512ifma avx512pf avx512vbmi avx512vl compile_examples enable_new_dtags f16c largefile rdrnd shani nostrip x86SimdAlways shared rpath release c++11 c++14 c++1z concurrent reduce_exports stl
Build options:
  Mode ................................... release
  Optimize release build for size ........ no
  Building shared libraries .............. yes
  Using C standard ....................... C11
  Using C++ standard ..................... C++1z
  Using ccache ........................... no
  Using gold linker ...................... no
  Using new DTAGS ........................ yes
  Using precompiled headers .............. no
  Using LTCG ............................. no
  Target compiler supports:
    SSE .................................. SSE2 SSE3 SSSE3 SSE4.1 SSE4.2
    AVX .................................. AVX AVX2
    AVX512 ............................... F ER CD PF DQ BW VL IFMA VBMI
    Other x86 ............................ AES F16C RDRAND SHA
    Intrinsics without -mXXX option ...... yes
  Build parts ............................ libs examples
Qt modules and options:
  Qt Concurrent .......................... yes
  Qt D-Bus ............................... no
  Qt D-Bus directly linked to libdbus .... no
  Qt Gui ................................. yes
  Qt Network ............................. yes
  Qt Sql ................................. yes
  Qt Testlib ............................. yes
  Qt Widgets ............................. yes
  Qt Xml ................................. yes
Support enabled for:
  Using pkg-config ....................... yes
  udev ................................... yes
  Using system zlib ...................... yes
Qt Core:
  DoubleConversion ....................... yes
    Using system DoubleConversion ........ no
  GLib ................................... no
  iconv .................................. yes
  ICU .................................... no
  Tracing backend ........................ <none>
  Logging backends:
    journald ............................. no
    syslog ............................... no
    slog2 ................................ no
  Using system PCRE2 ..................... yes
Qt Network:
  getifaddrs() ........................... yes
  IPv6 ifname ............................ yes
  libproxy ............................... no
  Linux AF_NETLINK ....................... yes
  OpenSSL ................................ yes
    Qt directly linked to OpenSSL ........ no
  OpenSSL 1.1 ............................ yes
  DTLS ................................... yes
  SCTP ................................... no
  Use system proxies ..................... yes
Qt Gui:
  Accessibility .......................... yes
  FreeType ............................... yes
    Using system FreeType ................ yes
  HarfBuzz ............................... no
    Using system HarfBuzz ................ no
  Fontconfig ............................. no
  Image formats:
    GIF .................................. no
    ICO .................................. yes
    JPEG ................................. yes
      Using system libjpeg ............... yes
    PNG .................................. yes
      Using system libpng ................ yes
  EGL .................................... yes
  OpenVG ................................. no
  OpenGL:
    Desktop OpenGL ....................... no
    OpenGL ES 2.0 ........................ yes
    OpenGL ES 3.0 ........................ yes
    OpenGL ES 3.1 ........................ yes
    OpenGL ES 3.2 ........................ yes
  Vulkan ................................. no
  Session Management ..................... yes
Features used by QPA backends:
  evdev .................................. yes
  libinput ............................... no
  INTEGRITY HID .......................... no
  mtdev .................................. no
  tslib .................................. no
  xkbcommon .............................. no
  X11 specific:
    XLib ................................. no
    XCB Xlib ............................. no
    EGL on X11 ........................... no
QPA backends:
  DirectFB ............................... no
  EGLFS .................................. yes
  EGLFS details:
    EGLFS OpenWFD ........................ no
    EGLFS i.Mx6 .......................... no
    EGLFS i.Mx6 Wayland .................. no
    EGLFS RCAR ........................... no
    EGLFS EGLDevice ...................... yes
    EGLFS GBM ............................ yes
    EGLFS VSP2 ........................... no
    EGLFS Mali ........................... no
    EGLFS Raspberry Pi ................... no
    EGLFS X11 ............................ no
  LinuxFB ................................ yes
  VNC .................................... yes
  Mir client ............................. no
Qt Sql:
  SQL item models ........................ yes
Qt Widgets:
  GTK+ ................................... no
  Styles ................................. Fusion Windows
Qt PrintSupport:
  CUPS ................................... no
Qt Sql Drivers:
  DB2 (IBM) .............................. no
  InterBase .............................. no
  MySql .................................. no
  OCI (Oracle) ........................... no
  ODBC ................................... no
  PostgreSQL ............................. no
  SQLite2 ................................ no
  SQLite ................................. no
    Using system provided SQLite ......... no
  TDS (Sybase) ........................... no
Qt Testlib:
  Tester for item models ................. yes
Qt QML:
  QML network support .................... yes
  QML debugging and profiling support .... yes
  QML sequence object .................... yes
  QML list model ......................... yes
  QML XML http request ................... yes
  QML Locale ............................. yes
  QML delegate model ..................... yes
Qt Quick:
  Direct3D 12 ............................ no
  AnimatedImage item ..................... yes
  Canvas item ............................ yes
  Support for Qt Quick Designer .......... yes
  Flipable item .......................... yes
  GridView item .......................... yes
  ListView item .......................... yes
  TableView item ......................... yes
  Path support ........................... yes
  PathView item .......................... yes
  Positioner items ....................... yes
  Repeater item .......................... yes
  ShaderEffect item ...................... yes
  Sprite item ............................ yes
Qt Quick Controls 2:
  Styles ................................. Default Fusion Imagine Material Universal
Qt Quick Templates 2:
  Hover support .......................... yes
  Multi-touch support .................... yes
Qt Tools:
  QDoc ................................... no

The configure command line in detail:

Command line: -v -opensource -confirm-license -force-pkg-config -hostprefix /top/bsp/local/qt/target -nomake tests -no-gif -no-harfbuzz -no-icu -no-pch -no-strip -skip qt3d -skip qtactiveqt -skip qtcanvas3d -skip qtconnectivity -skip qtdoc -skip qtimageformats -skip qtlocation -skip qtmacextras -skip qtmultimedia -skip qtscript -skip qtsensors -skip qtserialbus -skip qttranslations -skip qtwebchannel -skip qtwebengine -skip qtwebview -skip qtwinextras -skip qtx11extras -no-use-gold-linker -skip qtdatavis3d -skip qtgamepad -skip qtpurchasing -skip qtscxml -skip qtvirtualkeyboard -skip qtdocgallery -skip qtfeedback -skip qtnetworkauth -skip qtpim -skip qtqa -skip qtrepotools -skip qtspeech -skip qtsystems -skip qtandroidextras -examplesdir /usr/lib/qt5/examples -plugindir /usr/lib/qt5/plugins -prefix /usr -sysconfdir /etc/xdg -system-freetype -system-libjpeg -system-libpng -system-pcre -system-zlib -no-reduce-relocations -extprefix /top/fs/fsdev/usr -sysroot /top/fs/fsdev -no-gcc-sysroot -device ks-sdk -device-option CROSS_COMPILE= -device-option TARGET_COMPILER_CC=gcc-7 -device-option TARGET_COMPILER_CXX=g++-7 -device-option TARGET_COMPILER_LD=ld -device-option TARGET_COMPILER_AR=gcc-ar-7 -device-option TARGET_COMPILER_OBJCOPY=objcopy -device-option TARGET_COMPILER_NM=gcc-nm-7 -device-option TARGET_COMPILER_STRIP=strip -device-option 'TARGET_COMPILER_CFLAGS= -Wall -finput-charset=UTF-8 -g -O2  -isystem /top/fs/fsdev/include -isystem /top/fs/fsdev/usr/include -I/top/fs/fsdev/usr/include/freetype2 -I/top/fs/fsdev/usr/src/ti/include' -device-option 'TARGET_COMPILER_LDFLAGS=   -Wl,-rpath-link=/top/fs/fsdev/lib -Wl,-rpath-link=/top/fs/fsdev/usr/lib -Wl,-rpath-link=/top/fs/fsdev/lib/ -L/top/fs/fsdev/lib -L/top/fs/fsdev/usr/lib' -L/top/fs/fsdev/lib -L/top/fs/fsdev/usr/lib -no-opengl -skip qtwayland -opengl es2 -gbm -qpa eglfs -no-directfb -eglfs -evdev -kms -linuxfb -no-xcb -no-xcb-xlib -no-xcb-xinput -release -shared -no-cups -no-dbus -no-glib -openssl -no-sql-sqlite -skip qtcharts -skip qtserialport -skip qtxmlpatterns -no-tslib

Best,
Holger

[HolgerS]

I got a step further. The reason for the above error is that the appropriate device integration plugin is not loaded. To fix this, I set the environment variable:

QT_QPA_EGLFS_INTEGRATION=eglfs_kms

but got a new error:

qt.qpa_egldeviceintegration: Failed to load EGL device integration "eglfs_kms"
EGL library doesn't support emulator extensions
Aborted

So the plugin cannot be loaded, although it's there:

# ls /usr/lib/qt5/plugins/egldeviceintegrations
libqeglfs-emu-integration.so  libqeglfs-kms-egldevice-integration.so  libqeglfs-kms-integration.so

Any ideas?

[Pablo J. Rogina]

@HolgerS said in Qt on EGLFS without window manager:

I have an x86-based platform

Could it be possible to know more about the device? any links you could provide?

Any ideas?

Have you checked this forum?

There are a couple of posts (1, 2) with same error, although related to embedded devices., but that could lead you in same path regarding EGL drivers and plugin integration.

There's algo a Qt bug reported.

[HolgerS]

@Pablo-J-Rogina said in Qt on EGLFS without window manager:

@HolgerS said in Qt on EGLFS without window manager:

I have an x86-based platform

Could it be possible to know more about the device? any links you could provide?

My device is a standard (but customized) PC with Intel HD graphics. It is supposed to run only one application, therefore no need for Wayland or Xorg, which only add complexity.

[HolgerS]

I have found the solution.

First of all: The error message EGL library doesn't support emulator extensions does not come from the eglfs_kms plugin itself, but from the emulator plugin eglfs_emu which is used as a fallback, since the original plugin could not be loaded.

So why could eglfs_kms not be loaded in the first place?

The answer is that the library, resp. symlink libQt5EglFsKmsSupport.so.5 had not been deployed on my target device; therefore, loading the eglfs_kms plugin failed. Deploying the library with the appropriate symlink fixed the problem, i.e. the filesystem should look like this:

~ # ls -l /usr/lib/libQt5EglFsKmsSupport.so.5*
lrwxrwxrwx    ... /usr/lib/libQt5EglFsKmsSupport.so.5 -> libQt5EglFsKmsSupport.so.5.12.8
-rwxr-xr-x    ... /usr/lib/libQt5EglFsKmsSupport.so.5.12.8

I found this out by doing an strace on one of Qt's example applications:

export QT_QPA_EGLFS_INTEGRATION=eglfs_kms
strace /usr/lib/qt5/examples/widgets/tutorials/notepad/notepad 2>&1 | tee log.txt

and then greping for failed open-statements.

@Pablo-J-Rogina Thanks for your time!