Embedded Linux Sample Code

Applicable for

Apalis iMX6 | Apalis T30 | Colibri iMX6 | Colibri T20 | Colibri T30

BSP Layers / Reference Images for Yocto (Linux)

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GTK+ Example
1. To use it from within eclipse:
2. To use it from the command line:
OpenGL ES Samples

Article updated at 24 Jun 2019

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Some Embedded Linux sample code can be found in the Samples folder of our file download server:

Samples

For a cross toolchain see Build U-Boot and Linux Kernel from Source Code.

GTK+ Example

A make file project which compiles the scribble-simple.c from http://developer.gnome.org/gtk-tutorial.

Download gtk_scribble_V2.zip from our Samples page.

Makefile.ExtToolchain_Rootfs is a makefile suitable for use with an external cross toolchain and the rootfs contained in our image.
Set OECORE_TARGET_SYSROOT and CROSS_COMPILE to your needs.

Makefile.OE_Sysroot is a makefile suitable if you have built openembedded yourself. It uses the OpenEmbedded built cross toolchain, headers and target libraries.
Set OECORE_NATIVE_SYSROOT, OECORE_TARGET_SYSROOT and CROSS_COMPILE to your needs.

Make a symlink 'Makefile' pointed to the flavour you want to use. e.g.

ln -s Makefile.ExtToolchain_Rootfs Makefile

To use it from within eclipse:

In the Project Explorer:
- right click and chose import
- General/Existing Projects into Workspace
- Browse for the archive file gtk_scribble.zip
- Finish

In the Make Targets View you get make targets to compile for ARM and for x86.
'all' for x86 Linux,
'all.arm' for the Colibri T20.

To use it from the command line:

unzip the archive
for x86 Linux:

make CROSS_COMPILE=  all

for Colibri T20:

make all

OpenGL ES Samples

NVIDIA OpenGL ES 2.0 Samples

The sample programs from NVIDIA are available for download from our Samples page. These samples are only meant for the Tegra 2 and Tegra 3 Modules.

OpenEmbedded build

You can cross-compile and add the samples to a Linux image using OpenEmbedded.

How to build using OpenEmbedded

Read this article for OpenEmbedded setup.

Add the following line to the local.conf file:

 conf/local.conf
IMAGE_INSTALL_append = "nvsamples"

And build the Toradex image:

bitbake angstrom-lxde-image

Cross-compile from source

It might be useful to build from source when developing an application.

How to cross-compile from source

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.

In your home folder, download the samples and patches. Apply the patches:

wget -c http://developer1.toradex.com/files/toradex-dev/uploads/media/Colibri/Linux/Samples/nvsamples.tar.bz2
tar xjvf nvsamples.tar.bz2
cd nvsamples
wget -c http://developer1.toradex.com/files/toradex-dev/uploads/media/Colibri/Linux/Samples/nvsamples_armv7ahf_patches.tar.bz2
tar xjvf nvsamples_armv7ahf_patches.tar.bz2
patch -p1 < nvsamples-oe.patch
patch -p1 < nvsamples-no-binary-shaders.patch
patch -p1 < nvsamples-hardfp.patch

Warning: Make sure that you have run the patch commands inside the nvsamples directory.

Edit the file make/nvdefs.mk to adjust the NV_TOPDIR samples path:

 make/nvdefs.mk
NV_TOPDIR  = $(HOME)/nvsamples

Recompile the auxiliary tools:

cd samples/tools/nvtexfont2
make clean
make
cd ../nvgl2demo_common/
make clean
make
cd ../../../
ln -sf ~/nvsamples/samples/tools/nvtexfont2/libnvtexfont2.a lib-target/
ln -sf ~/nvsamples/samples/tools/nvgl2demo_common/libnvgl2demo_common.a lib-target/

Compile the samples:

cd samples/opengles2/
make clean
make

Copy the textures, shaders and binaries to the target. Change the IP address of the target accordingly:

cd ../../
mkdir textures shaders
cp -a samples/opengles2/ctree/textures/* textures/
cp -a samples/opengles2/bubble/textures/* textures/
cp -a samples/opengles2/ctree/*glsl? shaders/
cp -a samples/opengles2/bubble/*glsl? shaders/
cp -a samples/opengles2/gears/*glsl? shaders/
scp -r textures/ root@192.168.0.2:/home/root
scp -r shaders/ root@192.168.0.2:/home/root
scp samples/opengles2/ctree/ctree  root@192.168.0.2:/home/root
scp samples/opengles2/bubble/bubble  root@192.168.0.2:/home/root
scp samples/opengles2/gears/gears  root@192.168.0.2:/home/root

ARM's OpenGL ES 2.0 emulator and sampĺes

ARM provides an OpenGL ES emulator that maps OpenGL ES API calls to the OpenGL API, and it can be found here. It comes without samples, but you can also download the ARM Mali SDK for Linux, that is shipped with samples and can be built to run by the emulator but also on top of devices that support OpenGL ES and X11.

Cross-compile from source

It might be useful to build from source when developing an application.

How to cross-compile the samples

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...

NXP/Freescale's i.MX6 Graphics SDK

NXP/Freescale provides GPU SDKs shipped with OpenGL ES and OpenVG samples. You can build the samples from it for use on top of X11.

There are two versions of the GPU SDK, and both of them are available here, being:

The old SDK under the "Snippets, Boot Code, Headers, Monitors, etc." section and;
The new SDK under the "Software Development Kits" section once clicking "More".

At the time of writing, The old SDK revision is 1.0.0 (dated 01/25/2013) and the new SDK revision is 2.3 (dated 02/23/2016).

Cross-compile using the old SDK

The old SDK has OpenGL ES 1.1 and 2.0, and OpenVG samples. It is a Makefile based project with X11 and framebuffer support. Below are provided instructions on how to build the samples for X11.

How to cross-compile using the old SDK

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 the gpu_sdk_v1.00.tar.gz tarball from NXP/Freescale's website, under the Snippets, Boot Code, Headers, Monitors, etc. section: Software & Tools.

Create a directory and extract the tarball.

cd
mkdir gpu_sdk_v1.00
cd gpu_sdk_v1.00
tar xf ../gpu_sdk_v1.00.tar.gz

We're going to build the samples contained in the subdirectory 'Samples'.

The makefiles create executables for the softfp float ABI which is incompatible with our images. Thus change the CFLAGS in all makefiles to allow setting the ABI from the outside and also pass this information in the link step. Also, instead of unconditionally setting the CC and AR variables, allow the use of environment exported variables, for us to use the environment variables exported by the SDK.

cd; cd gpu_sdk_v1.00/Samples
find . -name "Makefile*" -exec sed -i 's/softfp/\$\(FLOATABI\)/' {} \;
find . -name "Makefile*" -exec sed -i 's/\-lstdc/\$\(CFLAGS_TUT\) -lstdc/' {} \;
find . -name "Makefile*" -exec sed -i 's/CC\ \=/CC\ ?\=/' {} \;
find . -name "Makefile*" -exec sed -i 's/AR\ \=/AR\ ?\=/' {} \;

Use the toplevel makefiles to set the float ABI. Add the following line to the top of gpu_sdk_v1.00/Samples/GLES1.1/Makefile.x11 and gpu_sdk_v1.00/Samples/GLES2.0/Makefile.x11:

export FLOATABI = hard

OpenGL ES 1.1

The toplevel makefile references two unavailable subprojects 18_VertexBufferObjects and 19_Beizer. Remove them from the SUB_PROJECTS variable.

Also, add the following line to the includes of main.h, for the 06_Projection, 11_LightingFog and 15_ParticleAccelerator samples. Otherwise, "‘GLshort’ does not name a type” error will be raised during compilation time:

#include <GLES/glext.h>

Make sure you have the SDK environment variables CC and AR set. Build the examples as follows:

cd; cd gpu_sdk_v1.00/Samples/GLES1.1
make -f Makefile.x11
make -f Makefile.x11 install

The executables can be found in gpu_sdk_v1.00/Samples/GLES1.1/bin/GLES11_x11/ ready for copying to your module.

OpenGL ES 2.0

The sample 05_PrecompiledShader does not link because the linker can not directly link the function glProgramBinaryOES. Adding the following to Samples/GLES2.0/05_PrecompiledShader/PrecompiledShader.c fixes this:

@@ -99,3 +99,5 @@ static GLuint LoadProgram(const char *programName)
long flength;M
+       // get the glProgramBinaryOES function
+       PFNGLPROGRAMBINARYOESPROC glProgramBinaryOES = (PFNGLPROGRAMBINARYOESPROC)eglGetProcAddress("glProgramBinaryOES");
// create the program objectM

Make sure you have the SDK environment variables CC and AR set. Build the examples as follows:

cd; cd gpu_sdk_v1.00/Samples/GLES2.0
make -f Makefile.x11
make -f Makefile.x11 install

The executables can be found in gpu_sdk_v1.00/Samples/GLES2.0/bin/GLES20_x11/ ready for copying to your module.

OpenVG

The X11 makefiles for the OpenVG samples are missing. Add them with the following patch:

cd; cd gpu_sdk_v1.00/Samples
wget https://docs.toradex.cn/102840-openvg_x11_patch.bz2
tar xf 102840-openvg_x11_patch.bz2
patch -p 1 < openvg_x11.patch

Make sure you have the SDK environment variables CC and AR set. Build the examples as follows:

cd; cd gpu_sdk_v1.00/Samples/OpenVG
make -f Makefile.x11
make -f Makefile.x11 install

The executables can be found in gpu_sdk_v1.00/Samples/OpenVG/bin/OpenVG_x11/ ready for copying to your module.

Cross-compile using the new SDK

The new SDK has OpenGL ES 2.0 and 3.0, and OpenVG samples. It has its Makefiles generated by Python scripts and supports Android SDK+NDK, Ubuntu, Windows and Yocto builds, being the latter possible for X11, framebuffer and Wayland. Below are provided instructions on how to build the samples for X11, using OpenEmbedded/Yocto.

How to cross-compile using the new SDK

You need an SDK to cross-compile from source. Read this article to build an image and SDK using OpenEmbedded. You will need to add additional packages to the standard recipe provided by Toradex at later steps.

Download the fsl-gpu-sdk-2.3.zip zip file from NXP/Freescale's website, under the Software Development Kits section once clicking More: Software & Tools.

Create a directory and extract the tarball following the instructions provided by the Readme.txt file, accepting the Freescale/NXP license:

unzip fsl-gpu-sdk-2.3.zip
chmod a+x fsl-gpu-sdk-2.3.bin
./fsl-gpu-sdk-2.3.bin
rm Readme.txt fsl-gpu-sdk-2.3.bin fsl-gpu-sdk-2.3.zip

Add dependencies to the OpenEmbedded build

Enter the SDK directory. Extract the OpenEmbedded layer meta-gtec and add it to your OpenEmbedded build. The instructions below are based in the documentation provided with the SDK (Doc/Setup_guide_yocto.txt).

cd; cd fsl-gpu-sdk-2.3
tar xzf meta-gtec.tar.gz
mv meta-gtec <your-openembedded-layers-directory>

Add the layer to bblayers.conf and the packages assimp and devil to local.conf:

 conf/bblayers.conf
...

BBLAYERS ?= " \
  ${TOPDIR}/../layers/meta-gtec \

...

 conf/local.conf
...

IMAGE_INSTALL_append = "assimp devil"

Build the angstrom-lxde-image and SDK. Flash the image to the iMX6 computer on module and install the SDK.

OpenGL ES 2, OpenGL ES 3 and OpenVG samples

Export the SDK and the ROOTFS and FSL_PLATFORM_NAME environment variables as described below, and source the prepare.sh script:

. <path-to-the-sdk-folder>/environment-setup-armv7at2hf-neon-angstrom-linux-gnueabi
export ROOTFS=<path-to-the-sdk-folder>/sysroots/armv7at2hf-neon-angstrom-linux-gnueabi
export FSL_PLATFORM_NAME=Yocto
. prepare.sh

There are some files that are lacking the cmath include, please add the following line to the files:

#include <cmath>

Files:

gedit ./DemoFramework/FslDemoHost/source/FslDemoHost/DemoAppProfilerOverlay.cpp ./DemoFramework/FslSimpleUI/source/FslSimpleUI/Control/CheckBox.cpp ./DemoFramework/FslGraphics3D/source/FslGraphics3D/Camera/ArcballCamera.cpp ./DemoFramework/FslGraphics_Draft/source/FslGraphics_Draft/Procedural/TorusGenerator.cpp ./DemoApps/Shared/FractalShaderShared/source/FractalShaderShared/ShaderUtil.cpp ./DemoApps/Shared/FractalShaderShared/source/FractalShaderShared/JuliaHelper.cpp ./DemoApps/Shared/EnvironmentMappingShared/source/EnvironmentMappingShared/SphereMeshCreator.cpp ./DemoApps/Shared/DFNativeBatch2DShared/source/DFNativeBatch2DShared/TextureAtlasScene.cpp ./DemoApps/Shared/DFGraphicsBasic2DShared/source/DFGraphicsBasic2DShared/Shared.cpp ./DemoApps/OpenVG/BitmapFont/source/BitmapFont.cpp ./DemoApps/GLES3/T3DStressTest/source/T3DStressTest.cpp ./DemoApps/GLES3/T3DStressTest/source/FurTexture.cpp ./DemoApps/GLES2/T3DStressTest/source/FurTexture.cpp ./DemoApps/GLES3/FurShellRendering/source/FurTexture.cpp ./DemoApps/GLES3/FurShellRendering/source/FurShellRendering.cpp ./DemoApps/GLES3/FractalShader/source/FractalShaderMandelbrot.cpp ./DemoApps/GLES3/E3_0_InstancingSimple/source/E3_0_InstancingSimple.cpp ./DemoApps/GLES3/T3DStressTest/source/T3DStressTest.cpp ./DemoApps/GLES2/T3DStressTest/source/T3DStressTest.cpp ./DemoApps/GLES2/FractalShader/source/FractalShaderMandelbrot.cpp ./DemoApps/GLES2/Blur/source/GausianHelper.cpp

To compile all the samples:

./build.sh -f GNUmakefile_Yocto -j 16 EGLBackend=X11

The OpenGL ES 2, OpenGL ES 3 and OpenVG executables are inside the DemoApps directory.

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