TODO didn't manage from source <Ubuntu 22.04>, their setup bitrotted way too fast... it's shameful even. Until I gave up and went for the magic <Docker> of + https://github.com/bbcmicrobit/micropython[], and it bloody worked:
``
git clone https://github.com/bbcmicrobit/micropython
cd micropython
git checkout 7fc33d13b31a915cbe90dc5d515c6337b5fa1660
docker pull ghcr.io/carlosperate/microbit-toolchain:latest
docker run -v $(pwd):/home --rm ghcr.io/carlosperate/microbit-toolchain:latest yt target bbc-microbit-classic-gcc-nosd@https://github.com/lancaster-university/yotta-target-bbc-microbit-classic-gcc-nosd
docker run -v $(pwd):/home --rm ghcr.io/carlosperate/microbit-toolchain:latest make all

# Build one.
tools/makecombinedhex.py build/firmware.hex examples/counter.py -o build/counter.hex
cp build/counter.hex "/media/$USER/MICROBIT/"

# Build all.
for f in examples/*; do b="$(basename "$f")"; echo $b; tools/makecombinedhex.py build/firmware.hex "$f" -o "build/${b%.py}.hex"; done
``

The pre-Docker attempts:
``
sudo add-apt-repository -y ppa:team-gcc-arm-embedded
sudo apt update
sudo apt install gcc-arm-embedded
sudo apt install cmake ninja-build srecord libssl-dev

# Rust required for some Yotta component, OMG.
sudo snap install rustup
rustup default 1.64.0

python3 -m pip install yotta
``

The line:
``
sudo add-apt-repository -y ppa:team-gcc-arm-embedded
``
warns:
``
E: The repository 'https://ppa.launchpadcontent.net/team-gcc-arm-embedded/ppa/ubuntu jammy Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
``
and then the update/`sudo apt-get install gcc-arm-embedded` fails, bibliography:
* https://askubuntu.com/questions/732985/force-update-from-unsigned-repository
* https://askubuntu.com/questions/1243252/how-to-install-arm-none-eabi-gdb-on-ubuntu-20-04-lts-focal-fossa

Attempting to install <Yotta (build system)>:
``
sudo -H pip3 install yotta
``
or:
``
python3 -m pip install --user yotta
``
was failing with:
``
Exception: Version mismatch: this is the 'cffi' package version 1.15.1, located in '/tmp/pip-build-env-dinhie_9/overlay/local/lib/python3.10/dist-packages/cffi/api.py'.  When we import the top-level '_cffi_backend' extension module, we get version 1.15.0, located in '/usr/lib/python3/dist-packages/_cffi_backend.cpython-310-x86_64-linux-gnu.so'.  The two versions should be equal; check your installation.
``
Running:
``
python3 -m pip install --user cffi==1.15.1
``
did not help. Bibliography:
* https://stackoverflow.com/questions/58552666/exception-version-mismatch-this-is-the-cffi-package-version-1-13-1
* https://github.com/ARMmbed/yotta/issues/289
* https://github.com/pyocd/pyOCD/issues/163
* http://docs.yottabuild.org/#installing-on-linux

From a clean <virtualenv>, it appears to move further, and then fails at:
``
Building wheel for cmsis-pack-manager (pyproject.toml) ... error
error: [Errno 2] No such file or directory: 'cargo'
``
So we install <Rust (programming language)> and try again, OMG:
``
sudo snap install rustup
rustup default stable
``
which at the time of writing was `rustc 1.64.0`, and then OMG, it worked!! We have the `yt` command.

However, it is still broken, e.g.:
``
git clone https://github.com/lancaster-university/microbit-samples
cd microbit-samples
git checkout 285f9acfb54fce2381339164b6fe5c1a7ebd39d5
cp source/examples/invaders/* source
yt clean
yt build
``
blows up:
``
annot import name 'soft_unicode' from 'markupsafe'
``
bibliography:
* https://github.com/aws/aws-sam-cli/issues/3661
* https://stackoverflow.com/questions/72191560/importerror-cannot-import-name-soft-unicode-from-markupsafe


 Discussion on "Compile MicroPython code for Micro Bit locally on Ubuntu 22.04 with your own firmware" by Ciro Santilli (@cirosantilli, 37)