Yocto Layer for Google Flutter related projects.

• Create a flutter workspace using flutter_workspace.py
• Debug and validate application running on your host machine using ivi-homescreen, flutter-auto, AGL QEMU, or Linux GTK.
• Create Yocto Recipe for your Flutter application using one of the pre-existing recipes as your template.
• Add your apps recipe and your selected embedder to IMAGE_INSTALL in your conf/local.conf file.
• Image device

• Flutter Application
• Flutter Web Application

• debug
• profile
• release
• jit_release

• core
• meta-python
• openembedded-layer

• clang-layer

• clang-layer

• gnome-layer

Zenity is used for fileselector plugin on ivi-homescreen. To enable this add meta-gnome to your layers.

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

• There are no OSS Linux embedders (that I am aware of that currently support software rendering). The engine does support it.

• flutter-auto is the agl branch of https://github.com/toyota-connected/ivi-homescreen the main branch has moved to quarterly releases, the agl branch is directly supporting AGL development work.

Targets flutter-engine-* is known to work on

• AGL QEMU images - aarch64/x86_64
• Intel icore7-64
• NVIDIA Nano, Xavier Dev Kits - aarch64
• NXP iMX7, iMX8; imx-weston requires patch for ivi-homescreen + flutter-auto
• Qualcomm DragonBoard DB410c, DB820, SA6155P, SA8xxx - aarch64
• Raspberry Pi 3 / Compute - aarch64 / armv7hf
• Raspberry Pi 4 / Compute - aarch64
• Raspberry Pi ZeroW / Zero2W - aarch64
• Renesas R-Car M3/H3 - aarch64
• STM32MP157x - cortexa7t2hf
• etc

Add to local.conf file:

TOOLCHAIN_HOST_TASK:append = " nativesdk-flutter-sdk"

Then run:

bitbake <image name> -c populate_sdk

Note: when using SDK you may need to add the following after installation:

$ export SDK_ROOT=<install folder>/sysroots/x86_64-nodistrosdk-linux/usr/share/flutter/sdk
$ git config --global --add safe.directory $SDK_ROOT

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

  INHERIT:remove = "uninative"

• The initial fetch with Flutter build will download over 14GB of source code. Running bitbake -C cleanall flutter-engine will clear the download cache. However, if an error occurs, the download cache remains intact, allowing you to resume the fetch later.

Please visit here.

Append this to your conf/local.conf

IMAGE_INSTALL:append = " packagegroup-flutter-sdk-deps"

You will also need to add dev packages to your platform that include libegl.so and libGLESv2.so. If the GPU driver for your platform is Mesa (such as Raspberry Pi 3/4/5), add these recipes to IMAGE_INSTALL in your conf/local.conf:

libegl-mesa-dev
libgles3-mesa-dev

From target terminal

cd ~
git clone https://github.com/flutter/flutter
cd flutter/bin
export PATH=$PATH:`pwd`
export GDK_GL=gles
flutter config --no-enable-android
flutter config --no-enable-web
flutter channel stable
flutter doctor -v

Test gallery app

cd ~
git clone https://github.com/flutter/gallery
cd gallery
flutter run -d linux

git clone https://github.com/meta-flutter/meta-flutter
cd meta-flutter

channel stable

tools/roll_meta_flutter.py

channel beta

tools/roll_meta_flutter.py --channel=beta

channel dev

tools/roll_meta_flutter.py --channel=dev

specific version

tools/roll_meta_flutter.py --version=2.40.0

This file is the origin of truth for all of the Flutter Applications present, and is used by tools/roll_meta_flutter.py.

roll_meta_flutter.py autogenerates all of the flutter application recipes.

• Update recipe SRCREV to desired version, rename recipe name to match
• Run bitbake on the recipe, it will likely fail
• Open terminal to path of src
• delete Cargo.lock
• delete toolchain file if present
• add the toolchain version used in yocto to your path ahead of any others
• Manually build the crate using this toolchain. This will create a new Cargo.lock against the toolchain version. This is a critical step.
• Run root-pkg-ws --manifest-path=/Cargo.toml
• Copy the output from this tool to the recipe file
• Rebuild and confirm it passes
• Submit PR with updated recipe

If you need a more recent Rust toolchain for Kirkstone, you can use

https://git.yoctoproject.org/git/meta-lts-mixins

The takeaway should be that Cargo.lock and toolchain versions are tightly coupled in Yocto. If you don't follow this in theory you could set network enable for compile, and set the cargo bbclass to auto-vend. This would break all LTS scenarios.