The Fuchsia emulator (FEMU) is the default emulator for Fuchsia. FEMU allows you to test Fuchsia components and applications without a physical Fuchsia device.
FEMU is included in the Fuchsia source tree. FEMU is downloaded (or updated) by jiri
, as part of jiri update
or jiri run-hooks
, and is fetched into the /prebuilt/third_party/aemu
directory of your Fuchsia source tree.
You can launch FEMU using ffx emu
.
FEMU is based on the Android Emulator (AEMU){:.external}, which is a fork of QEMU{:.external} – in some instances, such as debugging the Zircon kernel, you should use QEMU instead.
Due to legacy issues, there may be references to AEMU in the code and documentation.
If you want to debug the Zircon kernel, you should use fx qemu
instead. Read Debugging the Kernel using QEMU to learn more. This is for kernel developers. Most Fuchsia developers do not need to use this workflow.
FEMU looks and behaves like a Fuchsia device, except that no paving or flashing is required with FEMU.
The features of FEMU include:
--headless
argument).To see full list of supported flags:
ffx emu start --help
When setting up FEMU using fx set
, FEMU supports the following boards:
qemu-x64
qemu-arm64
With the Fuchsia SDK, FEMU supports pre-built images, including:
qemu-x64
workstation_eng.qemu-x64-release
qemu-arm64
ARM64 support (qemu-arm64
) is very limited and not recommended.
Use ffx product-bundle list
to see the full set of available products available from the SDK, and ffx product-bundle get {{ ‘’ }}product-bundle to download those products.
The --net
flag specifies the networking mode for the emulator. --net
requires a value to indicate which kind of networking to implement.
--net
has the following possible values:
tap
: Attaches a Tun/Tap interface.user
: Sets up mapped ports through SLiRP.none
: Disables networking.auto
: Checks the host system's capabilities and selects tap
if it is available or user
if a Tap interface is unavailable. auto
is the default.On Linux, FEMU should generally be run with the --net tap
flag that provides networking through an emulated NIC.
Note: Instructions for setting up networking for FEMU is in the Start the Fuchsia Emulator guide.
--net tap
and --net user
allow the emulator to be discoverable when running ffx target list
. --net none
disables networking, which causes the emulator to not be discoverable after running ffx target list
.
If starting the emulator with ffx emu start --net user
, an available TCP port from the host is picked and forwarded to the emulator's SSH port.
You can manually set the SSH address and use fx
tools to interact with your emulator by running the following command:
ffx emu start --net user --port-map {{ '<var>' }}PORT-NAME{{ '</var>' }}:{{ '<var>' }}PORT-NUMBER{{ '</var>' }}
Replace the following:
ssh
.8022
.Any named ports can be set the same way. The ports that can be mapped are named in the virtual device specification.
To verify that your fx
tool is using the correct port, run the following command:
ffx target get-ssh-address
You should see the SSH address printed next to Device name
.
To SSH into the emulator, run the following command:
fx shell
FEMU currently does not run on:
FEMU currently supports a limited set of GPUs on macOS and Linux for hardware graphics acceleration. FEMU uses a software renderer fallback for unsupported GPUs.
To launch FEMU, complete the Get started with Fuchsia guide.
Alternatively, you can use the Fuchsia SDK and use pre-built system images.
Once you're able to launch FEMU, you can perform the following tasks: