# Building Zephyr Out-of-Chroot

It is possible to build Zephyr outside of the Chromium OS chroot,
albeit with additional steps.

*** note
**Note:** These steps are maintained on a best-effort basis, and may
not be accurate depending on your Linux distribution and your system's
specific environment.
***

[TOC]

## Remove west, if installed [b/184654974](http://b/184654974)

Zephyr's Cmake system will try to attach itself to the west tool if it finds it
installed, conflicting with manual cmake invocations. If you installed west,
you'll need to remove it:

```bash
python3 -m pip uninstall west
```

## Install zmake

You can install zmake with pip:

```bash
cd ~/chromiumos/src/platform/ec
python3 -m pip install -e zephyr/zmake --user
```

Ensure that `~/.local/bin` is in your `PATH`.

You may also need to install these items:

```bash
sudo apt-get install cmake ninja-build python3-pyelftools gcc-multilib \
    python3-pykwalify python3-colorama python3-testfixtures
```

## Install binman

First build pylibfdt:

```bash
cd somewhere
sudo apt-get install flex bison swig
git clone git://git.kernel.org/pub/scm/utils/dtc/dtc.git
cd dtc
make
make install PREFIX=~/.local         # You can install this where it suits
```

If you have a Chromium OS checkout then you should do:

```bash
cd ~/.local/bin
ln -s ~/chromiumos/src/third_party/u-boot/files/tools/binman/binman
```

otherwise:

```bash
cd somewhere
git clone https://source.denx.de/u-boot/u-boot.git
cd ~/.local/bin
ln -s somewhere/u-boot/tools/binman/binman
```

## Install Zephyr toolchain

If using the Zephyr toolchain (`-t zephyr`), follow the [upstream
documentation] to install the Zephyr build tools.

[upstream documentation]: https://docs.zephyrproject.org/getting_started/index.html#install-a-toolchain