[Guide] How to build ChromiumOS

Download Ubuntu Server Flash your x86 system with it and start it:

sudo apt update && sudo apt upgrade -y && sudo apt install aptitude ubuntu-desktop -y
sudo reboot
sudo nano ~/.bashrc
export PATH="$HOME/depot_tools:$PATH"
umask 002
sudo nano /etc/profile
umask 022
sudo reboot

Making sudo a little more permissive

sudo aptitude install git-core gitk git-gui curl lvm2 thin-provisioning-tools python3-virtualenv python3-oauth2client nano screen xz-utils repo -y #python3.6 python-pkg-resources 
sudo git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git

sudo git config --global user.email "your@gmail.com"
sudo git config --global user.name "your_user"

cat > ./sudo_editor <<EOF 
#!/bin/sh
echo Defaults \!tty_tickets > \$1          
echo Defaults timestamp_timeout=180 >> \$1 
EOF

chmod +x ./sudo_editor
sudo EDITOR=./sudo_editor visudo -f /etc/sudoers.d/relax_requirements  

mkdir -p ~/chromiumos && cd ~/chromiumos
sudo repo init -u https://chromium.googlesource.com/chromiumos/manifest.git --repo-url https://chromium.googlesource.com/external/repo.git
sudo repo sync -j$(nproc)
#This will take time.

#sudo repo init -u https://chromium.googlesource.com/chromiumos/manifest.git --repo-url https://chromium.googlesource.com/external/repo.git [-b branch] # for example -b release-R90-13816.B
#sudo repo init -u https://chromium.googlesource.com/chromiumos/manifest.git --repo-url https://chromium.googlesource.com/external/repo.git -b release-R119-15633.B

List of all available manifests release-R119-15633.B


List of overlays available

#This will take a few hours the first time.
cros_sdk --enter
#Assume you already in the dir ~/chromiumos

cd ~/chromiumos/src/overlays/
cd ~/chromiumos/src/overlays/overlay-arm64-generic/
exit

cros_sdk ./set_shared_user_password.sh
#Setup “chronos” = root password, default is “test0000”.

cros build-packages '--board=arm64-generic'
cros build-image '--board=arm64-generic' --no-enable-rootfs-verification dev

If you want to build a package without boot verification: –noenable_rootfs_verification
You can choose dev (developer), test (the version with only default chronos password), base (like Chrome OS, without any modification) version.

🖱️Other Sources:🖱️ https://docs.google.com/document/d/1NbBYwml5jMitiFLV1jhkwldhFfq7XuQkRnJ72jQT3IU/edit?pli=1

https://medium.com/@KeithIMyers/a-guide-on-building-your-own-chromiumos-distribution-with-ota-updates-and-crostini-c1f1e1236af1

https://legacy.hacklog.in/post/download-build-chromium-os/