Yocto Layer for Google Flutter related projects.

Updates:

• FLUTTER_CHANNEL support has been deprecated

• FLUTTER_SDK_TAG - New approach. Allows locking SDK and Engine to specific commit hash. Valid values for FLUTTER_SDK_TAG are here: https://github.com/flutter/flutter/tags

• Flutter Engine Commit If FLUTTER_SDK_TAG is set to "AUTOINC" or not defined in local.conf, the engine commit used is master channel. Otherwise the engine.version file in flutter/flutter is used to set the engine commit.

• build failure due to gn unknown parameter for --no-build-embedder-examples. One solution to resolve this is to exclude disable-embedder-examples from PACKAGECONFIG in local.conf using:

  PACKAGECONFIG_pn-flutter-engine-release = "disable-desktop-embeddings embedder-for-target fontconfig release"
  
  PACKAGECONFIG_pn-flutter-engine-debug = "disable-desktop-embeddings embedder-for-target fontconfig debug"
  
  PACKAGECONFIG_pn-flutter-engine-profile = "disable-desktop-embeddings embedder-for-target fontconfig profile"
  

  This issue is related to missing gn options --build-embedder-examples and --no-build-embedder-examples from certain builds. I have disable-embedder-examples defined in PACKAGECONFIG by default, so if you have an engine commit that is missing this option, you need to use the PACKAGECONFIG sequence above. Once the gn option rolls into all channels this override will no longer be needed.

• When using the Sony embedders you need to specify FLUTTER_RUNTIME that matches other elements being installed, or make image will fail with package conflict. Example to avoid conflict with other recipes:

  echo 'FLUTTER_RUNTIME_pn-flutter-drm-gbm-backend = "debug"' >> ./conf/local.conf
  echo 'FLUTTER_RUNTIME_pn-flutter-wayland-client = "debug"' >> ./conf/local.conf
  

• Build Flutter application using desktop tools
• Use Flutter Engine Runtime=Debug build confirming it works on target. Debug as needed using customdevices
• Create Yocto Recipe for your Flutter application using flutter-gallery-* as the template. Nested projected are supported using FLUTTER_APPLICATION_PATH. Passing Dart defines are done with FLUTTER_EXTRA_BUILD_ARGS.
• Add flutter-gallery, selected embedder, flutter-engine runtime=Release to your release image.
• Image device

Note: If you get a gray screen running the Gallery app, chances are you don't have a locale set. Ensure your platform has a valid locale set. See GLIBC_GENERATE_LOCALES and IMAGE_LINGUAS in one of the NVidia CI projects on how to do this.

Note: In theory Swift Shader (CPU render) engine builds should work with the right build flags. Be warned it won't work out of the box. Select a SoC with a GPU that supports OpenGL 3.0+ and save yourself the Engineering NRE.

• meta-clang

Clang generates smaller runtime images, and is used by Google to build the the flutter engine for Android and iOS. Changing toolchains should be avoided, as this would provide a path with little to no test milage. If you are trying to port the flutter-engine to QNX 7.0 feel free to contact me.

Target BSP is expected to have a GPU with OpenGLES v2.0+ support.
If you selecting a part go with v3.0+, ideally one with Vulkan support.

This layer includes recipes to build

• flutter-sdk (channel selection, default is master if FLUTTER_SDK_TAG is not set)
• flutter-engine (tracks engine.version from FLUTTER_SDK_TAG)
• flutter-gallery Application (debug, profile, and release) requires master
• ivi-homescreen (Toyota/AGL - Wayland Embedder)
• flutter-pi (DRM w/VSync - Recommended embedder for DRM)
• flutter-wayland (POC) / waylandpp/ipugxml (archived)
• Sony embedders

• dunfell-agl-aarch64.yml - AGL emaultor build that uses non-locked values. This is used as health gate for rolling commits in AGL. No Vulkan support.

• dunfell-agl-x86_64.yml - AGL emaultor build that uses non-locked values. This is used as health gate for rolling commits in AGL. No Vulkan support.

• dunfell-dart-mx8m-mini.yml - Variscite DART-MX8M-MINI (NXP iMX8) Weston build + ivi-homescreen. No Vulkan support.

• dunfell-linux-dummy.yml - meta-flutter canary CI job builds all recipes against linux-dummy kernel

• dunfell-nvidia-jetson-nano-devkit.yml - NVidia Jetson Nano Devkit weston build with ivi-homescreen and Vulkan suport.

• dunfell-nvidia-jetson-xavier-nx-devkit.yml - NVidia Jetson Xavier NX Devkit weston build with ivi-homescreen and Vulkan suport.

• dunfell-rpi4-64.yml - Raspberry PI4 EGL/DRM build with Flutter-pi and Vulkan (Mesa 21.2) support.

• dunfell-stm32mp15.yml - ST Microelectronics STM32MP15 EGL and Weston builds. EGL build has flutter-pi (currently has rendering issues), and Weston build has ivi-homescreen which works beautifully.

For more Raspberry PI images see the Honister branch.

Targets flutter-engine-* is known to work on

• AGL QEMU images - aarch64/x86_64 (CI job)
• DragonBoard 410c - aarch64
• Intel MinnowBoard Max (BayTrail) - intel-icore7-64
• NVIDIA Nano Dev Kit - aarch64 (CI job)
• NVIDIA Xavier NX Dev Kit - aarch64 (CI job)
• Raspberry Pi 3 / Compute - aarch64 / armv7hf (CI job)
• Raspberry Pi 4 / Compute - aarch64 (CI job)
• Renesas R-Car m3ulcb - aarch64
• STM32MP157x - cortexa7t2hf (CI job)
• etc, etc

Note: 32-bit ARM builds were broken for a period, so if you have build issues only with 32-bit try moving to a newer tag.

Add to local.conf file:

TOOLCHAIN_HOST_TASK_append = " flutter-sdk-nativesdk"

Then run:

bitbake <image name> -c populate_sdk

See dunfell-stm32mp15.yml (CI job) for more detail

See Wiki for flashing image and using customdevice: https://github.com/meta-flutter/meta-flutter/wiki/STM32MP1-Disco-Notes

repo init -u https://source.codeaurora.org/external/imx/imx-manifest -b imx-linux-gatesgarth -m imx-5.10.9-1.0.0.xml
repo sync -j20
DISTRO=fslc-wayland MACHINE=imx8qxpmek source setup-environment build
pushd ../sources
git clone -b dunfell https://github.com/meta-flutter/meta-flutter.git
popd
echo -e 'FLUTTER_SDK_TAG = "2.10.0-0.2.pre"' >> conf/local.conf
echo -e 'IMAGE_INSTALL_append = " flutter-engine-debug ivi-homescreen-debug flutter-gallery-debug"' >> conf/local.conf
bitbake-layers add-layer ../sources/meta-clang ../sources/meta-flutter
bitbake fsl-image-multimedia

See honister branch README.md and CI jobs for more detail

When building on systems with GCC version > than uninative in Yocto distro add the following to conf/local.conf

INHERIT_remove = "uninative"