Networking with Arm FVP User Mode
This page is intended to serve as a starting point for anyone interested in using Arm FVP user mode networking with Zephyr.
Introduction
User mode networking emulates a built-in IP router and DHCP server, and routes TCP and UDP traffic between the guest and host. It uses the user mode socket layer of the host to communicate with other hosts. This allows the use of a significant number of IP network services without requiring administrative privileges, or the installation of a separate driver on the host on which the model is running.
By default, Arm FVP uses the 172.20.51.0/24 network and runs a gateway at
172.20.51.254. This gateway also functions as a DHCP server for the GOS,
allowing it to be automatically assigned with an IP address 172.20.51.1.
More details about Arm FVP user mode networking can be obtained from here: https://developer.arm.com/documentation/100964/latest/Introduction-to-Fast-Models/User-mode-networking
Using Arm FVP User Mode Networking with Zephyr
Arm FVP user mode networking can be enabled in any applications and it doesn’t need any configurations on the host system. This feature has been enabled in DHCPv4 client sample. See DHCPv4 client sample application.
Limitations
You can use TCP and UDP over IP, but not ICMP (ping).
User mode networking does not support forwarding UDP ports on the host to the model.
You can only use DHCP within the private network.
You can only make inward connections by mapping TCP ports on the host to the model. This is common to all implementations that provide host connectivity using NAT.
Operations that require privileged source ports, for example NFS in its default configuration, do not work.
If setup fails, or the parameter syntax is incorrect, there is no error reporting.