Extend
This document provides the guides showing how to use extra features, customize configurations in this software stack.
Extra Features
Networking
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 root@localhost -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 \
'bp.virtio_net.hostbridge.userNetPorts=8022=22,8080=80,5555=5555'"
Note
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 \
'bp.virtiop9device.root_path=/path/to/host-mount-dir'"
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).
Note
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.
Note
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" \
XEN_DOM0LESS_ZEPHYR_APPLICATION="zephyr-helloworld" \
kas build v8r64/meta-armv8r64-extras/kas/virtualization.yml