Note: The following instructions assume you have the OpenEmbedded SDK environment variables exported.

You need an SDK to cross-compile from source. Read this article to build an SDK for your image using OpenEmbedded.

Download and extract the ARM MALI samples, that are shipped in the ARM Mali SDK for Linux:

cd ~
wget -c https://developer.arm.com/-/media/Files/downloads/mali-sdk/v2.4.4/Mali_OpenGL_ES_SDK_v2.4.4.ef7d5a_Linux_x64.tar.gz
tar xzf Mali_OpenGL_ES_SDK_v2.4.4.ef7d5a_Linux_x64.tar.gz
cd Mali_OpenGL_ES_SDK_v2.4.4

You have to modify some configuration files in order to use the OpenEmbedded cross-toolchain.

In the target cmake file "arm-linux.cmake" below, the GCC_COVERAGE_COMPILE_FLAGS was set based on the CC environment variable set by the target SDK. It may need to be adjusted according to your target (for instance, you can set -mfpu=neon for SoCs that have this co-processor integrated).

 ./arm-linux.cmake
...

set (GCC_COVERAGE_COMPILE_FLAGS "-mfpu=vfpv3-d16 -march=armv7-a -mthumb -mfpu=vfp  -mfloat-abi=hard $ENV{CFLAGS}")
set (GCC_COVERAGE_LINK_FLAGS    $ENV{LDFLAGS})
set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${GCC_COVERAGE_COMPILE_FLAGS}")
set (CMAKE_CXX_FLAGS  "${CMAKE_CXX_FLAGS} ${GCC_COVERAGE_COMPILE_FLAGS}")
set (CMAKE_EXE_LINKER_FLAGS  "${CMAKE_EXE_LINKER_FLAGS} ${GCC_COVERAGE_LINK_FLAGS}")

set (CMAKE_SYSROOT "$ENV{TOOLCHAIN_ROOT}/sysroots/armv7at2hf-vfp-angstrom-linux-gnueabi/")

set (CMAKE_CXX_COMPILER "${TOOLCHAIN_ROOT}/sysroots/x86_64-angstromsdk-linux/usr/bin/arm-angstrom-linux-gnueabi/arm-angstrom-linux-gnueabi-g++")
set (CMAKE_C_COMPILER "${TOOLCHAIN_ROOT}/sysroots/x86_64-angstromsdk-linux/usr/bin/arm-angstrom-linux-gnueabi/arm-angstrom-linux-gnueabi-gcc")

set (CMAKE_FIND_ROOT_PATH "${TOOLCHAIN_ROOT}/sysroots/armv7at2hf-vfp-angstrom-linux-gnueabi/")

...

It is also required to use the X11 libraries, since the Toradex pre-built image comes with LXDE:

 ./CMakeLists.txt
...

else(${TARGET} STREQUAL "arm")
    # Linux on ARM
    set (GLES_LIB "libGLESv2.so")
    set (EGL_LIB "libEGL.so")

    set(DUMMY_MALI_LIBRARIES GLESv2 EGL)
    add_subdirectory(lib/arm)
    set (OPENGLES_LIBRARIES ${DUMMY_MALI_LIBRARIES})
    include_directories(simple_framework/inc/mali)
    set (PLATFORM_LIBRARIES X11 m)
endif()

...

In the samples directory, modify the cmake file samples/CMakeLists.txt if you want to supress the build of OpenGL ES 3.0 and 3.1 samples. This might be required since some embedded GPUs only support up to OpenGL ES 2.0.

 ./samples/CMakeLists.txt
add_subdirectory(opengles_20)
#add_subdirectory(opengles_30)
#add_subdirectory(opengles_31)

We need to tell cmake to use DesktopLinuxPlatform.cpp instead of LinuxOnARMPlatform.cpp. This is done by editing the CMakeLists.txt file inside the simple_framework directory:

 ./simple_framework/CMakeLists.txt
...

elseif(${TARGET} STREQUAL "arm")
    file(GLOB PLATFORM_SOURCES
        src/DesktopLinuxPlatform.cpp
    )
endif()

...

It is also required to change some compiler directives for the source-code to use X11 instead of the framebuffer. See the diff comparison between original and modified files, and change yours accordingly:

 ./simple_framework/src/Platform.cpp
@@ -19,8 +19,6 @@
     {
     #if defined(_WIN32)
         return WindowsPlatform::getInstance();
-    #elif defined(__arm__) && defined(__linux__)
-        return LinuxOnARMPlatform::getInstance();
     #elif defined(__linux__)
         return DesktopLinuxPlatform::getInstance();
     #endif

 ./inc/EGL/eglplatform.h
@@ -83,14 +83,7 @@
 typedef void *EGLNativeWindowType;
 typedef void *EGLNativePixmapType;

-#elif defined(__arm__) && defined(__gnu_linux__)  /* ARM Linux Mali */
-#include <EGL/fbdev_window.h>
-
-typedef void*         EGLNativeDisplayType;
-typedef void*         EGLNativePixmapType;
-typedef fbdev_window* EGLNativeWindowType;
-
-#elif defined(__unix__)
+#elif defined(__linux__)

 /* X11 (tentative)  */
 #include <X11/Xlib.h>

 ./simple_framework/inc/Platform.h
@@ -42,8 +42,6 @@
     #if defined(_WIN32)
         HWND window;
         HDC deviceContext;
-    #elif defined(__arm__) && defined(__linux__)
-        fbdev_window *window;
     #elif defined(__linux__)
         Window window;
         Display* display;
@@ -83,9 +81,6 @@
 #if defined(_WIN32)
 #include "WindowsPlatform.h"

-#elif defined(__arm__) && defined(__linux__)
-#include "LinuxOnARMPlatform.h"
-
 #elif defined(__linux__)
 #include "DesktopLinuxPlatform.h"

 ./simple_framework/src/EGLRuntime.cpp
@@ -219,9 +219,6 @@
 #if defined(_WIN32)
         /* Win32 */
         display = eglGetDisplay(platform->deviceContext);
-#elif defined(__arm__)
-        /* Linux on ARM */
-        display = eglGetDisplay(EGL_DEFAULT_DISPLAY);
 #else
         /* Desktop Linux */
         platform->display = XOpenDisplay(NULL);
@@ -278,14 +275,9 @@
          * On ARM devices perform a strict match to ensure we get the best performance.
          * On desktop devices perform a loose match to ensure greatest compatability.
          */
-#if defined(__arm__)
-        config = findConfig(true);
-#else
+#if defined(__linux__)
         config = findConfig(false);
-#endif
-
-#if defined(__linux__) && !defined(__arm__)
-        ((DesktopLinuxPlatform*)(platform))->createX11Window();
+       ((DesktopLinuxPlatform*)(platform))->createX11Window();
 #endif

         /* Create a surface. */

Create a directory for the build and run cmake inside it:

mkdir build_arm
cd build_arm
cmake -G "Unix Makefiles" -DTARGET=arm ..
make install

Copy the application to the target. Change the IP address of the target accordingly:

scp -r ../bin_arm root@192.168.0.2:/home/root

Note: You must run each application inside its own directory. Otherwise it will not find the shaders, etc...