How to Compile OpenWrt Firmware

Why Compile OpenWrt Yourself

There are several reasons to compile OpenWrt yourself:

• Customization: Users can choose which software packages to install according to their needs, resulting in a smaller firmware file size.

• Updates: If you want to use the latest kernel version or other software, you can compile it yourself.

• Security: If you want to ensure the security of your device, compiling it yourself guarantees that the firmware has no vulnerabilities.

• Learning: Compiling firmware is a great opportunity to understand how the system works.

In summary, compiling OpenWrt yourself allows users to have better control over their devices and helps improve their skills.

Reasons Not to Compile OpenWrt Yourself

I do not recommend users compile OpenWrt firmware themselves; rather, I hope users will use the firmware provided by the official website for the following reasons:

1. There is no difference in execution efficiency between self-compiled and officially compiled firmware.

   Generally, the official recommendation is to use the ImageBuilder (firmware generator) to generate firmware, which is used as an alternative to source cross-compilation, to:

   Using the firmware generator can avoid additional system resource consumption and reduced system efficiency due to unreasonable configurations.

   If you only want to compile a specific software, you can try using the OpenWrt SDK, which can save time during the deployment of the compilation environment.

• Accommodate more software in smaller firmware.

• The device has only 32MB or less RAM and lacks opkg functionality.

In summary, unless there is a specific need, I do not wish for users to compile OpenWrt firmware themselves. However, if there are (but not limited to) the following situations, self-compilation is the only option:

• Compared to generic firmware, there are significant differences that prevent OpenWrt from booting, such as using relatively obscure hardware (e.g., some uncommon Ethernet interfaces), or the device requires other special support, such as adding support for human interaction devices, large storage, and more hard disk format support;

• Hoping to deeply customize or optimize the code;

• The software being used requires kernel or driver support to run.

Preparation

A computer or virtual machine (preferably Debian or Ubuntu; this article uses Ubuntu as an example).

Compilation Steps (Global Scientific Approach Recommended)

Configure the Required Environment for Compilation

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sudo apt-get install subversion g++ zlib1g-dev build-essential git python3 python3-distutils rsync man-db libncurses5-dev gawk gettext unzip file libssl-dev wget zip time libssh-dev 

It is recommended to update the system software in advance:

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sudo apt update
sudo apt upgrade

Download Source Code

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git clone https://github.com/openwrt/openwrt.git
sudo chmod 777 openwrt  # Give highest permissions

Add Required Applications

It is recommended to organize all the programs that need to be compiled at once and add them all at once, as back-and-forth operations waste a lot of time!

This article takes compiling the luci-theme-argon theme as an example:

Run the following commands sequentially:

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cd openwrt/package
git clone https://github.com/jerrykuku/luci-theme-argon.git

Then run the following commands:

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./scripts/feeds clean
./scripts/feeds update -a
./scripts/feeds install -a

Configuration

Input:

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make menuconfig

Basic Operation Instructions for the Interface:

• Use the up and down arrow keys to select items, and the left and right arrow keys to exit and save;

• If you want to compile plugins to write into the firmware, press Y;

• If you only want to compile without writing into the firmware, press M;

• If you do not want to compile or cancel an already built-in selection, press N;

Make simple selections:

1. Select Target System, I am using x86, select x86;

2. Select Subtarget, choose x86_64, also based on your model;

   Generic is only suitable for 32-bit hardware (old hardware or certain Atom processors) and should be used for i586 Linux architecture, running on Pentium 4 and above. This feature should only be used if your hardware cannot run the 64-bit version.

   Legacy is for very old PC hardware before Pentium 4, referred to as i386 in Linux architecture support. It will miss many features desired/needed on modern hardware, such as multi-core support and support for more than 1GB of RAM, but will actually run on older hardware where other versions will not.

3. Add the management interface: select LuCI under Image Configuration – Collections

   

   

4. If you want to add a Chinese language pack, select Modules – Translations

   

   

5. Go to Themes, select luci-theme-argon

   

6. Select Save and exit.

   

   It is strongly recommended to carefully review each setting; missing components or cores can easily lead to problems!

Other settings generally do not need to be modified; you can refer to:

Compilation

Finally, input:

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make  V=s  -j4
# V=s: This can output the execution actions of each step during the compilation process, showing detailed error information when an error occurs.
# -j4: Use 4 threads for parallel compilation, significantly speeding up the compilation process.
# The whole process takes about 1-2 hours.

General Process and Precautions for Compilation:

General process:

The compilation process first checks the compilation environment, then compiles the host tools, then compiles the compilation toolchain, and finally compiles various software packages for the target platform. When compiling with make, it first downloads the code package, then unzips it, applies patches, generates the Makefile based on the settings, and finally compiles and installs according to the generated Makefile.

Precautions:

During compilation, an internet connection is required because OpenWrt uses patch packages to manage code. Third-party code is not stored in its own code repository but is only downloaded from third-party servers before compilation (during compilation, software module code is downloaded from the Internet because OpenWrt only has compilation and configuration instructions, and various dependency code packages are located in upstream websites and code repositories. The OpenWrt website also has third-party code package mirrors, which will use OpenWrt’s own server address when upstream websites are unavailable, with the download address being http://downloads.openwrt.org/sources/).

Compilation Complete

After compilation is complete, you may find several files in the ./openwrt/bin/targets/x86/64/ folder:

Testing

Copy the firmware version you need; I tested it on a virtual machine without issues. This time it was just a simple configuration, and there were no packages… Of course, this does not affect anything, and you can directly install via command line through SSH.

Cloud Compilation

Of course, you can also perform cloud compilation; refer to:

OpenWrt official cloud compilation address: https://firmware-selector.openwrt.org/

In Conclusion

Once again, I emphasize that I do not recommend compiling, as it is time-consuming and labor-intensive. This article merely touches on the basics of compilation, and further exploration is necessary.

Unless absolutely necessary, do not compile…