Contents

• Prerequisites
• Prepare your build environment (once per build environment)
• Get the Source
• Build Fuchsia
• Build
• Boot Fuchsia
• Installing and booting from hardware
• Boot from QEMU
• Explore Fuchsia
• Change some source
• Select a tab
• Launch a graphical component
• Running tests
• Contribute changes
• Additional helpful documents

Prerequisites

Debian

sudo apt-get install build-essential curl git python unzip

macOS

1. Install Command Line Tools:

   xcode-select --install
   

2. In addition to Command Line Tools, you also need to install a recent version of Xcode.

Follow the instructions to get the Fuchsia source and then return to this document.

Note: A quick overview of the basic build-and-pave workflow can be found here.

If you added .jiri_root/bin to your path as part of getting the source code, the fx command should already be in your path. If not, the command is also available as scripts/fx.

fx set x64
fx full-build

The first command selects the build configuration you wish to build and generates the build system itself in an output directory (e.g., out/debug-x64).

The second command actually executes the build, transforming the source code in build products. If you modify the source tree, you can do an incremental build by re-running the fx full-build command alone.

Alternatively, you can use the underlying build system directly.

[optional] Customize Build Environment

By default you will get a x64 debug build. You can skip this section unless you want something else.

Run fset-usage to see a list of build options. Some examples:

fx set x64                 # x64 debug build
fx set arm64               # arm64 debug build
fx set x64 --release       # x64 release build

[optional] Accelerate builds with ccache and goma

ccache accelerates builds by caching artifacts from previous builds. ccache is enabled automatically if the CCACHE_DIR environment variable is set and refers to a directory that exists.

[Googlers only: goma accelerates builds by distributing compilation across many machines. If you have goma installed in ~/goma, it is used by default. It is also used by default in preference to ccache.]

To override the default behaviors, pass flags to fx set:

--ccache     # force use of ccache even if goma is available
--no-ccache  # disable use of ccache
--no-goma    # disable use of goma

If you don’t have the supported hardware, you can run Fuchsia under emulation using QEMU. Fuchsia includes prebuilt binaries for QEMU under buildtools/qemu.

The fx run command will launch Zircon within QEMU, using the locally built disk image:

fx run

There are various flags for fx run to control QEMU’s configuration:

• -m sets QEMU’s memory size in MB.
• -g enables graphics (see below).
• -N enables networking (see below).

Use fx run -h to see all available options.

QEMU tips

• ctrl+a x will exit QEMU in text mode.
• ctrl+a ? or ctrl+a h prints all supported commands.

Enabling Graphics

Note: Graphics under QEMU are extremely limited due to a lack of Vulkan support. Only the Zircon UI renders.

To enable graphics under QEMU, add the -g flag to fx run:

fx run -g

Enabling Network

First, configure a virtual interface for QEMU’s use.

Once this is done you can add the -N and -u flags to fx run:

fx run -N -u $FUCHSIA_SCRIPTS_DIR/start-dhcp-server.sh

The -u flag runs a script that sets up a local DHCP server and NAT to configure the IPv4 interface and routing.

When Fuchsia has booted and displays the “$” shell prompt, you can run programs!

For example, to receive deep wisdom, run:

fortune

To shutdown or reboot Fuchsia, use the dm command:

dm help
dm shutdown

Almost everything that exists on a Fuchsia system is stored in a Fuchsia package. A typical development workflow involves re-building and pushing Fuchsia packages to a development device or QEMU virtual device.

Make a change to the rolldice binary in garnet/bin/rolldice/src/main.rs.

In a separate shell, start the development update server, if it isn’t already running:

fx serve -v

Re-build and push the rolldice package to a running Fuchsia device with:

fx build-push rolldice

From a shell prompt on the Fuchsia device, run the updated package with:

run rolldice

Fuchsia shows multiple tabs after booting with graphics enabled. The currently selected tab is highlighted in yellow at the top of the screen. You can switch to the next tab using Alt-Tab on the keyboard.

• Tab zero is the console and displays the boot and component log.
• Tabs 1, 2 and 3 contain shells.
• Tabs 4 and higher contain components you’ve launched.

Note: to select tabs, you may need to enter “console mode”. See the next section for details.

QEMU does not support Vulkan and therefore cannot run our graphics stack.

Most graphical components in Fuchsia use the Mozart system compositor. You can launch such components, commonly found in /system/apps, like this:

launch spinning_square_view

Source code for Mozart example apps is here.

When you launch something that uses Mozart, uses hardware-accelerated graphics, or if you build the default package (which will boot into the Fuchsia System UI), Fuchsia will enter “graphics mode”, which will not display any of the text shells. In order to use the text shell, you will need to enter “console mode” by pressing Alt-Escape. In console mode, Alt-Tab will have the behavior described in the previous section, and pressing Alt-Escape again will take you back to the graphical shell.

If you would like to use a text shell inside a terminal emulator from within the graphical shell you can launch the term by selecting the “Ask Anything” box and typing moterm.

Compiled test binaries are installed in /pkgfs/packages/. You can run a test by invoking it in the terminal. E.g.

/pkgfs/packages/ledger_tests/0/test/ledger_unittests

If you want to leave Fuchsia running and recompile and re-run a test, run Fuchsia with networking enabled in one terminal, then in another terminal, run:

fx run-test <test name> [<test args>]

You may wish to peruse the testing FAQ.

• See CONTRIBUTING.md.