Explore OpenWrt on Emulated hardware

This blog will help to run OpenWrt on emulated hardware

Posted Mar 17, 2025

By Dineshkumar Loganathan

5 min read

OpenWrt - An overview

OpenWrt (Open Wireless RouTer) is an open-source project for creating an embedded operating systems based on Linux. OpenWrt is designed for embedded devices, particularly routers and is capable to run in range of hardware products, be it low memory Wi-Fi routers, CPE routers, residential gateways, access points and so on. In this article, the possibilities of booting up a router operating system like OpenWrt without a physical hardware is unravelled.

Features of OpenWrt

Below are the few key features of OpenWrt

Configuration over command line interface (or) web interface(LuCI)
Customization
Performance and Stability
Advanced Networking Features like firewall, VLAN, VPN, QoS and so on
Enhanced Security
Mesh Networking
Package Management using opkg/apkg package manager

Unleash OpenWrt on non-physical hardware

While OpenWrt is primarily designed for embedded devices like routers, it’s not strictly limited to real hardware and can also be run in virtual machines (VMs), emulator, or on x86 hardware. OpenWrt provides QEMU packages for ARM and x86 platforms to explore the OS without the need of real hardware’s using emulators.

QEMU (Quick EMUlator) is a powerful, open-source processor emulator and virtualizer. QEMU can emulate various CPU architectures (like x86, ARM and so on) and hardware devices allowing you to run software and operating systems designed for those architectures on your current system.

This articles helps us to emulate OpenWrt using qemu in Arm SystemReady target

Arm SystemReady

Arm SystemReady (or) armsr is an openwrt target that is developed based on Arm SystemReady compliance program where an Operating System image will be compatible across ARM based hardware manufacturers.

Arm SystemReady is implemented in alignment with the two OS environment and firmware approaches commonly used to generate and install the OS Images. These are split into the following bands

OpenWrt uses the SystemReady Devicetree band, where the preferred method of booting the OS is based on the hardware devicetree.

Arm SystemReady on OpenWrt

armsr takes over from the previous armvirt target in OpenWrt and adds support for Arm systems that support booting EFI images. armsr supports the below subtargets

armv7 for 32-bit machines
armv8 for 64-bit machines

QEMU can be used to emulate armsr target running OpenWrt without the needs for real hardware.

Refer OpenWrt Target → armsr → README to get the detailed instructions on how to boot the OpenWrt SystemReady image.

Running OpenWrt using qemu

For Running OpenWrt on QEMU, we can use armsr-armv8 as a reference target to boot and analyse OpenWrt OS.

Prebuilt Images are available and can be downloaded from the OpenWrt’s Snapshot downloads for armsr-armv8.

Download the below image files from the OpenWrt link for emulating armsr target using qemu.

openwrt-armsr-armv8-generic-squashfs-combined-efi.img.gz
u-boot-qemu_armv8/u-boot.bin

Decompress the generic-squashfs-combined-efi.img.gz into openwrt-arm-64.img

gunzip -c openwrt-armsr-armv8-generic-squashfs-combined-efi.img.gz > openwrt-arm-64.img

Emulate OpenWrt for armsr-armv8 target using qemu-system-aarch64 command with the default arguments for kernel, rootfs image, cpu and network options.

qemu-system-aarch64 -nographic \
    -cpu cortex-a53 -machine virt \
    -bios u-boot.bin \
    -smp 1 -m 1024 \
    -device virtio-rng-pci \
    -drive file=openwrt-arm-64.img,format=raw,index=0,media=disk \
    -netdev user,id=testlan -net nic,netdev=testlan \
    -netdev user,id=testwan -net nic,netdev=testwan

Walkthrough OpenWrt bootlog for armsr-armv8

OpenWrt is successfully booted for armsr-armv8 target.
Below excerpt from the OpenWrt bootlog, covers the following stages of booting,
- Booting : U-Boot
- Booting : Linux kernel with version Linux version 6.6.83
- OpenWrt prompt

U-Boot 2023.04-OpenWrt-r29028-adc4d95c74 (Mar 16 2025 - 21:43:02 +0000)

DRAM:  1 GiB
Core:  51 devices, 14 uclasses, devicetree: board
Flash: 64 MiB
Loading Environment from Flash... *** Warning - bad CRC, using default environment

In:    pl011@9000000
Out:   pl011@9000000
Err:   pl011@9000000
Net:   eth0: virtio-net#32, eth1: virtio-net#33
Hit any key to stop autoboot:  0

.... skipped ....

EFI stub: Booting Linux Kernel...
EFI stub: Using DTB from configuration table
EFI stub: Exiting boot services...
[    0.000000] Booting Linux on physical CPU 0x0000000000 [0x410fd034]
[    0.000000] Linux version 6.6.83 (builder@buildhost) (aarch64-openwrt-linux-musl-gcc (OpenWrt GCC 13.3.0 r29028-adc4d95c74) 13.3.0, GNU ld (GNU Binutils) 2.42) #0 SMP Sun Mar 16 21:43:02 2025
[    0.000000] KASLR enabled
[    0.000000] Machine model: linux,dummy-virt

.... skipped ....

[    0.004525] printk: console [tty1] enabled
[    0.004786] printk: bootconsole [pl11] disabled
Please press Enter to activate this console.

BusyBox v1.37.0 (2025-03-16 21:43:02 UTC) built-in shell (ash)

  _______                     ________        __
 |       |.-----.-----.-----.|  |  |  |.----.|  |_
 |   -   ||  _  |  -__|     ||  |  |  ||   _||   _|
 |_______||   __|_____|__|__||________||__|  |____|
          |__| W I R E L E S S   F R E E D O M
 -----------------------------------------------------
 OpenWrt SNAPSHOT, r29028-adc4d95c74
 -----------------------------------------------------
=== WARNING! =====================================
There is no root password defined on this device!
Use the "passwd" command to set up a new password
in order to prevent unauthorized SSH logins.
 -----------------------------------------------------

root@OpenWrt:~#

OpenWrt version and board details

The openwrt version and board_name related details from the ARMSR system,

root@OpenWrt:~# cat /etc/openwrt_release
DISTRIB_ID='OpenWrt'
DISTRIB_RELEASE='SNAPSHOT'
DISTRIB_REVISION='r29028-adc4d95c74'
DISTRIB_TARGET='armsr/armv8'
DISTRIB_ARCH='aarch64_generic'
DISTRIB_DESCRIPTION='OpenWrt SNAPSHOT r29028-adc4d95c74'
DISTRIB_TAINTS=''
root@OpenWrt:~# cat /etc/openwrt_version
r29028-adc4d95c74
root@OpenWrt:~# cat /tmp/sysinfo/board_name
linux,dummy-virt

Ethernet

IP Address is assigned to the WAN Interface of the Target device.
And Target device could able to reach Internet through WAN Network.

root@OpenWrt:~# ifconfig eth1
eth1      Link encap:Ethernet  HWaddr 52:54:00:12:34:57
          inet addr:10.0.2.15  Bcast:10.0.2.255  Mask:255.255.255.0
          inet6 addr: fec0::5054:ff:fe12:3457/64 Scope:Site
          inet6 addr: fe80::5054:ff:fe12:3457/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:184 errors:0 dropped:0 overruns:0 frame:0
          TX packets:229 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:17075 (16.6 KiB)  TX bytes:22998 (22.4 KiB)

root@OpenWrt:~# ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8): 56 data bytes
64 bytes from 8.8.8.8: seq=0 ttl=255 time=8.390 ms
.... skipped ....

root@OpenWrt:~# ping -c 3 google.com
PING google.com (142.250.196.78): 56 data bytes
64 bytes from 142.250.196.78: seq=0 ttl=255 time=5.849 ms
64 bytes from 142.250.196.78: seq=1 ttl=255 time=8.664 ms
64 bytes from 142.250.196.78: seq=2 ttl=255 time=8.852 ms

--- google.com ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max = 5.849/7.788/8.852 ms

A New OpenWrt Beginning

With OpenWrt running on qemu, It opens up a way to explore OpenWrt without real hardware and allows for endless option to tweak and tune your experiments.

References

blog, tutorial

This post is licensed under CC BY 4.0 by the author.