Running OpenWRT on Virtual and Physical Devices

Introduction to QEMU for Embedded Emulation

Overview:

• QEMU (Quick Emulator) is an open-source emulator for running virtual machines, supporting architectures like ARM, MIPS, and x86.
• In OpenWRT, QEMU is used to emulate embedded devices for development and testing.

Why Use QEMU for Embedded Emulation?

• Development and Testing: Allows testing OpenWRT images without physical hardware.
• Simulation and Debugging: Provides a controlled environment for debugging firmware and applications.
• Cross-Compilation: Supports testing cross-compiled software on emulated platforms.
• Virtualization: Enables running multiple OpenWRT instances on a single host.

QEMU Architecture:

• Emulated CPU: Simulates processors (e.g., ARM Cortex-A, MIPS).
• Emulated Memory: Provides virtual RAM and flash storage.
• Emulated I/O Devices: Simulates network interfaces, serial ports, and storage devices.
• Emulated Firmware: Supports U-Boot or other bootloaders for realistic boot emulation.

Benefits:

• Reduces dependency on physical hardware for development.
• Enables rapid prototyping and testing of OpenWRT features.
• Supports multiple architectures for broad compatibility.

Installing and Booting into OpenWRT in QEMU

To emulate and test OpenWRT without using physical hardware, follow our step-by-step guide on setting up OpenWRT in QEMU. This includes downloading the appropriate image, configuring QEMU, and booting into the virtualized environment.

👉 View the full guide

Flashing Images to Physical Devices (u-boot, tftp, serial)

1. Preparing the Device

   Before flashing the image, ensure that the device is properly configured and the necessary tools are available.

2. Booting the Device into U-Boot

   To flash the image, the device needs to be booted into U-Boot. This can be done by pressing the reset button or by using a JTAG debugger.

3. Loading the Image using TFTP

   Once the device is booted into U-Boot, the image can be loaded using TFTP. The TFTP server needs to be configured to serve the image file.

4. Flashing the Image

   After the image is loaded, it can be flashed to the device using the U-Boot flash command.

5. Verifying the Flash

   After the image is flashed, it can be verified by checking the device’s configuration and functionality.

Console Access and SSH Login

1. Accessing the Console

   To access the console, the device needs to be booted into U-Boot or the operating system.

2. Configuring the Console

   The console needs to be configured to use the correct serial port and baud rate.

3. Logging in via SSH

   Once the console is accessible, it can be logged in via SSH using a secure shell client.

Recovering from Failed Flash / Soft Bricking

1. Identifying the Problem

   The first step is to identify the problem and determine the cause of the failed flash or soft bricking.

2. Booting into U-Boot

   To recover from a failed flash or soft bricking, the device needs to be booted into U-Boot.

3. Loading the Recovery Image

   The recovery image needs to be loaded using TFTP or other means.

4. Flashing the Recovery Image

   The recovery image needs to be flashed to the device using the U-Boot flash command.

5. Verifying the Recovery

   After the recovery image is flashed, it can be verified by checking the device’s configuration and functionality.