Basically this is short notes about building Chromium OS (a.k.a Chrome OS), all refer to Chromium OS Developer Guide

Environment

$ sudo apt-get install git-core gitk git-gui subversion curl
$ git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git
$ export PATH=`pwd`/depot_tools:"$PATH"   # better to add it into .bashrc

Source

$ mkdir -p chromiumos && cd chromiumos
$ repo init -u https://chromium.googlesource.com/chromiumos/manifest.git --repo-url https://chromium.googlesource.com/external/repo.git
$ repo sync

Build

enter chroot

$ ./chromite/bin/cros_sdk

board select

$ export BOARD=x86-generic      # change board depend on your device, pick one from overlays
$ ./setup_board --board=${BOARD}
$ ./build_packages --board=${BOARD}
$ ./build_image --board=${BOARD} --noenable_rootfs_verification dev

download

$ cros flash usb:// ${BOARD}/latest     # then boot your device by this USB key

Clean

$ # delete chroot, do *NOT* use rm -rf chroot
$ cros_sdk --delete

Enlarge ccache size

ccache is used to speedup chromiumos 2nd build, typical build will spend 9GB space, however the default size is 1GB only, you can enlarge it manually

$ ccache --max-size=10G
$ export CCACHE_DIR=/var/cache/distfiles/ccache
$ ccache -s