This document provides the guides showing how to use extra features, customize configurations in this software stack.

Extra Features


The FVP is configured by default to use “user mode networking”, which simulates an IP router and DHCP server to avoid additional host dependencies and networking configuration. Outbound connections work automatically, e.g. by running:

wget www.arm.com

Inbound connections require an explicit port mapping from the host. By default, port 8022 on the host is mapped to port 22 on the FVP, so that the following command will connect to an ssh server running on the FVP:

ssh [email protected] -p 8022

To map other ports from host, add the parameter containing the port mapping in the command as below:

kas shell -k \
    v8r64/meta-armv8r64-extras/kas/virtualization.yml \
    -c "../layers/meta-arm/scripts/runfvp \
        --verbose --console -- --parameter \


User mode networking does not support ICMP, so ping will not work.

More details on this topic can be found at User mode networking 1.

File Sharing between Host and FVP

It is possible to share a directory between the host machine and the FVP using the virtio P9 device component included in the kernel. To do so, create a directory to be mounted from the host machine:

mkdir /path/to/host-mount-dir

Then, add the following parameter containing the path to the directory when launching the model:

--parameter 'bp.virtiop9device.root_path=/path/to/host-mount-dir'

e.g. for the virtualization build:

kas shell -k \
    v8r64/meta-armv8r64-extras/kas/virtualization.yml \
    -c "../layers/meta-arm/scripts/runfvp \
        --verbose --console -- --parameter \

Once you are logged into the FVP, the host directory can be mounted in a directory on the model using the following command:

mount -t 9p -o trans=virtio,version=9p2000.L FM /path/to/fvp-mount-dir

Customize Configuration

Customizing the Zephyr Configuration

The Zephyr repository contains two relevant board definitions, fvp_baser_aemv8r and fvp_baser_aemv8r_smp, each of which provides a base defconfig and device tree for the build. In the Yocto build, the board definition is selected dynamically based on the number of CPUs required by the application recipe.

The defconfig can be extended by adding one or more .conf files to SRC_URI (which are passed to the OVERLAY_CONFIG Zephyr configuration flag).


The file extension for Zephyr config overlays (.conf) is different to the extension used by config fragments in other recipes (.cfg), despite the similar functionality.

The device tree can be modified by adding one or more .overlay files to SRC_URI (which are passed to the DTC_OVERLAY_FILE Zephyr configuration flag). These overlays can modify, add or remove nodes in the board’s device tree.

For an example of these overlay files and how to apply them to the build, see the modifications to run Zephyr applications on Xen at the path v8r64/meta-armv8r64-extras/dynamic-layers/virtualization-layer/recipes-kernel/zephyr-kernel/

The link Important Build System Variables 2 provides more information.


Zephyr’s device tree overlays have a different syntax from U-Boot’s device tree overlays.

Customizing the Xen Domains

The default configuration contains two pre-configured domains: XEN_DOM0LESS_DOM_LINUX and XEN_DOM0LESS_DOM_ZEPHYR, with the BitBake varflags set appropriately. These varflags define where to find the domain binaries in the build configuration, where to load them in memory at runtime and how to boot the domain. Note that no attempts are made to validate overlapping memory regions, or even whether the defined addresses fit in the FVP RAM. For information, see the notes in the file v8r64/meta-armv8r64-extras/classes/xen_dom0less_config.bbclass.

Currently, the default images that these two pre-configured domains run on are: one Linux rootfs image (core-image-minimal) for XEN_DOM0LESS_DOM_LINUX and one Zephyr application (zephyr-synchronization) for XEN_DOM0LESS_DOM_ZEPHYR.

The default Linux rootfs image can be configured using the variable XEN_DOM0LESS_LINUX_IMAGE and the default Zephyr application can be configured using the variable XEN_DOM0LESS_ZEPHYR_APPLICATION. For example, to use core-image-base and zephyr-helloworld instead of the defaults, run:

XEN_DOM0LESS_LINUX_IMAGE="core-image-base" \
    kas build v8r64/meta-armv8r64-extras/kas/virtualization.yml