Fuchsia Build System

These are notes on using the gen.py script and ninja directly for builds, and the scripts/run-zircon-* scripts to launch QEMU.

You can alternatively use the standard build instructions, which use the fx commands instead.

Build Zircon and the sysroot

First, you need to build the Zircon kernel and the sysroot:

(cd zircon; make -j32 zircon-pc-x86-64)
./scripts/build-zircon.sh

Build Fuchsia

Build Fuchsia using these commands:

./packages/gn/gen.py
./buildtools/ninja -C out/debug-x86-64

Optionally if you have ccache installed and configured (i.e. the CCACHE_DIR environment variable is set to an existing directory), use the following command for faster builds:

./packages/gn/gen.py --ccache
./buildtools/ninja -C out/debug-x86-64

[Googlers only] If you have goma installed, prefer goma over ccache and use these alternative commands for faster builds:

./packages/gn/gen.py --goma
./buildtools/ninja -j1024 -C out/debug-x86-64

The gen.py script takes an optional parameter ‘--target_cpu’ to set the target architecture. If not supplied, it defaults to x86-64.

./packages/gn/gen.py --target_cpu=aarch64
./buildtools/ninja -C out/debug-aarch64

You can configure the set of packages that gen.py uses with the --packages argument. After running gen.py once, you can do incremental builds using ninja.

You can specify an “autorun” script to run at startup with the --autorun parameter. The argument to --autorun is the path to a shell script. This simple example powers off the machine immediately after booting.

echo 'dm poweroff' > poweroff.autorun
./packages/gn/gen.py --autorun=poweroff.autorun
./buildtools/ninja -C out/debug-x86-64

For a list of all gen.py options, run gen.py --help.

Running Fuchsia

The commands above create an out/debug-{arch}/user.bootfs file. To run the system with this filesystem attached in QEMU, pass the path to user.bootfs as the value of the -x parameter in Zircon's start command script, for example:

./scripts/run-zircon-x86-64 -x out/debug-x86-64/user.bootfs -m 2048
./scripts/run-zircon-arm64 -x out/debug-aarch64/user.bootfs -m 2048

See the standard build instructions for other flags you can pass to QEMU.

Running on ARM Hardware

To build a fuchsia image for a particular ARM hardware target, you must also provide the zircon project name for that particular target to gen.py via the zircon_project argument. For example, to build a fuchsia image for the HiKey 960, you might invoke gen.py as follows:

./packages/gn/gen.py --zircon_project=zircon-hikey960-arm64 --target_cpu=aarch64
./buildtools/ninja -C out/debug-aarch64