Build steps:

• Copy Dockerfile from the repo to a local directory
• Build docker container:

docker build -t mp157_build .

• Launch the container:

docker run -t -i -v $PWD/build_volume:/build_volume mp157_build /bin/bash

Inside container:

git clone https://github.com/ValentiWorkLearning/stm32mp1dk2_buildroot_bootlin.git
cd stm32mp1dk2_buildroot_bootlin
git submodule update --init
cd buildroot 
git checkout st/2022.02.7
git cherry-pick f986b265511e6f4748595c8b7ea83f1f616ddd64
cd ..

export REPO_ROOT=${PWD}
make BR2_EXTERNAL=${REPO_ROOT}/buildroot-external-st -C buildroot O=/test_build st_stm32mp157c_dk2_demo_defconfig
cd /test_build
make
cp /test_build/images/sdcard.img /build_volume/