Getting Started with BSP Screen

A beginner's guide to locating and applying the screen configuration details to set up your BSP to use graphics.

Screen support packages

A Board Support Package (BSP) provides support for running the QNX OS on a particular hardware platform. The BSP package provides the essential files needed for development on the board, along with extra support and utility files you can choose to install. Additional packages may be needed to support some activities, which may or may not be available for your board. An example is the Screen Support package, a BSP-specific package customized to support graphics on a specific QNX BSP.

You can check the QSC required for the use and development of graphics. For graphics, a BSP Screen Support package is also needed.

Not all boards and BSPs have graphic support available, but you can search the QSC for an appropriate Screen Support Package. This package provides support for a particular board or group of boards, along with the originally downloaded BSP.

A BSP Screen Support package provides the board customization needed to extend a base Screen package to work with the target board and its BSP. There may be other packages needed for the combined support of a board for graphics development. These combinations, and the test hardware configuration can be found in the BSP Screen Release Note.

Screen Support Release Notes

To find the details of what support packages are needed for a Screen BSP Support Package, see the BSP Screen Release Note provided with the BSP Screen Package. The release note will list the packages needed, as well as show the supported hardware setup the embedded system has been tested with.

A BSP Screen Support Release Note provides the following key information:

  • The hardware and BSP that this package supports.
  • The Package ID for the Screen Support package.
  • The Package ID for the required Screen base package.
  • The supported hardware configuration this package was tested with.
  • Any known issues and available workarounds.
  • BSP integration and Screen configuration.
Note:
BSP-specific release notes, including BSP Screen Support release notes can be found with the BSP documentation online. Broader SDP-level notes, such as for a Screen Base package are found under SDP Release notes.

Screen configuration

The default buildfile (bsp-pathname.build) provided with your BSP doesn't build an image that starts the Screen Graphics Subsystem (Screen). Instead, you must use the image that's built from the bsp-screen-pathname-graphics.build file, which starts Screen automatically.

The Screen Graphics Subsystem (Screen) includes the libraries, services and tools required to run graphics applications on the board with supported graphics processors, and to manage graphics shown on the display. To use Screen, you often must configure the graphics and display. To confirm whether Screen is running properly on your target, use the provided demo applications in your BSP package that you can run on the target. This is a brief overview of how to use Screen on your target, but for detailed information, you should refer to the Screen Graphics Subsystem Developer's Guide in the QNX Software Development Platform 8.0 documentation.

Note:
To get the correct binaries and graphics configuration file for your board, install the appropriate Screen Board Support package for this board from the QNX Software Center. For information about how to determine the Screen Board Support package to install for this board, see the Screen release notes. After you install the Screen Board Support package, the $QNX_TARGET/aarch64le/usr/lib/graphics/bsp-filename/ directory will contain the drivers and graphics configuration you require. It's important to note that these binaries are necessary for you to build your BSP with graphics.

Graphics configuration

The specifics of a board’s graphics configuration, such as the target's output display port or the output resolution, are defined in the graphics configuration file (graphics.conf). The graphics configuration file and required Screen binaries are found in the $QNX_TARGET/arch64le/usr/lib/graphics/bsp-filename directory on your host installation. On the target, the same binaries and configuration are typically located at /usr/lib/graphics/bsp-pathname/. Before you start Screen, you must ensure that the LD_LIBRARY_PATH environment variable includes the path to the Screen binaries. In the example buildfile, this has been done for you, but if you haven't done this, you can set the path before starting Screen using these commands:

# export LD_LIBRARY_PATH=/proc/boot:/lib:/usr/lib:/lib/dll:/lib/dll/pci:\
                         /usr/lib/graphics/bsp-filename
# screen -c /usr/lib/graphics/bsp-filename/graphics.conf
The supported resolutions per display can be found in this file. Screen needs to be restarted for any change in graphics configuration to take effect as follows: 
# slay screen
# screen -c /usr/lib/graphics/$BSP_ID/graphics.conf

For more information about the Screen Graphics Subsystem, see the Screen Graphics Subsystem Developer’s Guide in the QNX Software Development Platform 8.0 documentation.

Configure the display for Screen

For the graphics.conf file, the video-mode setting must match the screen resolution and frame rate supported by the display that's connected to your board. Screen reads these parameters from the graphics.conf file to initialize the display drivers. Supported resolutions and frame rates for this BSP are listed in the Screen Support Release Notes. A commonly supported HDMI display resolution in the graphics.conf file is:
  • 1920x1080 @ 60 (default for HDMI output)
For example, for a 1920 x 1080 @ 60 Hz display, set the video-mode in the graphics.conf file as shown here:
...
...
...
begin display 1
  formats = rgba8888, rgbx8888, rgb565, rgba5551, yuy2, uyvy, nv12
  video-mode = 1920 x 1080 @ 60
  cursor = off
end display
...
...
For more information about configuring the display subsection in the graphics.conf, see Configure display subsection in the Screen Graphics Subsystem Developer's Guide.

Display driver

The video display configuration library is located on the target at /usr/lib/graphics/bsp-filename/libwfdcfg-bsp-filename.so and /usr/lib/graphics/bsp-filename/libWFD$BSP_ID.so.

Using the GPU

Your board requires several graphics libraries to run applications that utilize the GPU, and are they are listed in the $BSP_ROOT_DIR/images/bsp-filename-graphics.build file of your BSP package. The list will be similar to this example:
  • $QNX_TARGET/aarch64le/usr/lib/graphics/bsp-filename/libglslcompiler.so
  • $QNX_TARGET/aarch64le/usr/lib/graphics/bsp-filename/libIMGegl.so
  • $QNX_TARGET/aarch64le/usr/lib/graphics/bsp-filename/libIMGGLESv1_CM.so
  • $QNX_TARGET/aarch64le/usr/lib/graphics/bsp-filename/libIMGGLESv2.so
  • $QNX_TARGET/aarch64le/usr/lib/graphics/bsp-filename/libPVROCL.so
  • $QNX_TARGET/aarch64le/usr/lib/graphics/bsp-filename/libPVRScopeServices.so
  • $QNX_TARGET/aarch64le/usr/lib/graphics/bsp-filename/libpvrSCREEN_WSEGL.so
  • $QNX_TARGET/aarch64le/usr/lib/graphics/bsp-filename/libsrv_km.so
  • $QNX_TARGET/aarch64le/usr/lib/graphics/bsp-filename/libsrv_um.so
  • $QNX_TARGET/aarch64le/usr/lib/graphics/bsp-filename/libufwriter.so
  • $QNX_TARGET/aarch64le/usr/lib/graphics/bsp-filename/libVK_IMG.so
  • $QNX_TARGET/aarch64le/usr/lib/graphics/bsp-filename/libWFDbsp-filename.so
  • $QNX_TARGET/aarch64le/usr/lib/graphics/bsp-filename/libwfdcfg-bsp-filename.so
  • $QNX_TARGET/aarch64le/usr/lib/graphics/bsp-filename/rgx_vulkan_icd.json
  • $QNX_TARGET/aarch64le/usr/lib/graphics/bsp-filename/screen-jacinto7-alloc.so

Run Screen applications

The BSP archive contains built-in demo applications that show how to use Screen. It's a good idea to run these demos on your target to confirm that Screen is configured properly and all the necessary drivers are available for Screen to run. If the following demo applications run successfully, it's a good indication that Screen is properly configured on your target.

sw-vsync
Shows vsync that uses software rendering, but doesn't use GLES. This application is useful to verify that your display works with basic Screen functionality.
Figure 1sw-vsync


gles2-gears
Shows gears that use OpenGL ES 2.X for the rendering API; if gles2-gears runs, then it confirms that screen and drivers necessary for OpenGL ES 2.x have started successfully.
Figure 2gles2-gears


For more information about using the demo applications or debugging them, see the Utilities and Binaries and the Debugging chapters in the Utilities and Binaries and the Debugging chapters in the Screen Developer's Guide, respectively.

Create Screen applications

When you create an application that supports Screen, it must link to the Screen library (libscreen.so). This library provides the interfaces for applications to use the Screen API. Depending on the graphical requirements of your application, you may need to link in additional libraries. Below are some of the libraries commonly used when building applications that use Screen:
libEGL
The interface to access vendor-specific EGL functionality. Refer to the EGL standard from www.khronos.org.
libGLESv2
The interface to access vendor-specific OpenGL ES functionality. Refer to the OpenGL ES standard from www.khronos.org.
libimg
The interface to load and decode images. For more information, see the Image Library Reference guide in the QNX Software Development Platform 8.0 documentation.

For more information about application development using Screen, see the Screen Graphics Subsystem Developer’s Guide. For information about linking libraries, see QNX C/C++ Project properties in the Reference chapter of the QNX Momentics IDE User's Guide or the Compiling and Debugging chapter of the QNX OS Programmer's Guide.

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