OpenWrt Package Creation: A Quick Guide

This post outlines the process of building and deploying a custom C/C++ package on an OpenWrt-enabled HLK-7628N development board. To set up a build environment quickly, you just need to download the openwrt-sdk for your hardware platform. In this case, I'm using the HLK-7628N dev board, whose sdk and firmware can be downloaded from the OpenWrt website.

1. Download SDK and Firmware

First, get the necessary files.

• Go to the OpenWrt Downloads page.

• Navigate to your device's target (e.g., targets/ramips/mt76x8).

• Download the SDK for your specific release (e.g., openwrt-sdk-*-ramips-mt76x8_gcc-*-musl.Linux-x86_64.tar.zst).

• Download the firmware image (squashfs-sysupgrade.bin) for your board, if you need to flash it.

2. Extract the SDK

Extract the downloaded SDK archive to your desired working directory.

tar --zstd -xfv openwrt-sdk-*-mt7628_gcc-*-musl.Linux-x86_64.tar.xz
cd openwrt-sdk-* # Navigate into the extracted SDK directory

3. Create Package Folder and Add to Feeds

Create your package directory and integrate it with the SDK's build system.

# Create your package directory
mkdir -p /path/to/sdk/my_custom_feed
src-link my_custom_feed /path/to/sdk/my_custom_feed
# Update and install feeds (ensure you're in the SDK root)
./scripts/feeds update -a
./scripts/feeds install -a

4. Write the Package Makefile and Source Code

Place your C++ source code and the OpenWrt Makefile in the my_custom_feed/my-first-app directory.

my_custom_feed/my-first-app/main.cpp

#include <iostream>

int main(int argc, char* argv[]) {
    std::cout << "Hello from the HLK-7628!" << std::endl;
    return 0;
}

my_custom_feed/my-first-app/CMakeLists.txt

cmake_minimum_required(VERSION 3.5)
project(my-first-app CXX)

add_executable(my-first-app main.cpp)
install(TARGETS my-first-app  DESTINATION /usr/bin)

my_custom_feed/my-first-app/Makefile

include $(TOPDIR)/rules.mk

PKG_NAME:=my-first-app
PKG_VERSION:=1.0
PKG_RELEASE:=1


SOURCE_DIR:=$(TOPDIR)/my_custom_feed/my-first-app
PKG_BUILD_DIR:=$(BUILD_DIR)/$(PKG_NAME)-$(PKG_VERSION)

include $(INCLUDE_DIR)/package.mk
# You can include different mk file for different build systems...
include $(INCLUDE_DIR)/cmake.mk

define Package/my-first-app
       SECTION:=utils        
       CATEGORY:=Utilities
       TITLE:=My First Custom Application
       DEPENDS:=+libstdcpp # or other libs
endef

define Build/Prepare
         mkdir -p $(PKG_BUILD_DIR)
        cp -r $(SOURCE_DIR)/* $(PKG_BUILD_DIR)/
endef


define Package/my-first-app/install
  $(INSTALL_DIR) $(1)/usr/bin
  $(INSTALL_BIN) $(PKG_BUILD_DIR)/my-first-app $(1)/usr/bin/
endef

$(eval $(call BuildPackage,my-first-app))

5. Select the Package and Build

Configure the SDK to build your package and then compile it.

# From the SDK root directory:
make menuconfig

• Navigate to Utilities.

• Find my-first-app and select it by pressing M (to build as a module/package).

• Save and exit.

# Build the package (from the SDK root directory)
./scripts/feeds update my_custom_feed
./scripts/feeds install my-first-app
make package/my-first-app/compile V=s

Your .ipk package will be in bin/packages/mipsel_24kc/my_custom_feed/.

6. Push to Device, Install, and Test

Transfer the package to your HLK-7628, install it, and verify functionality.

# Copy the .ipk to your device (replace with actual IP and filename)
scp bin/packages/mipsel_24kc/my_custom_feed/my-first-app_1.0-1_mipsel_24kc.ipk root@<router_ip>:/tmp/

# SSH into your device
ssh root@<router_ip>

# Install the package
opkg install /tmp/my-first-app_1.0-1_mipsel_24kc.ipk

# Run your application
my-first-app

You should see: Hello from the HLK-7628!

Now that you've seen how to build and deploy your own package, the possibilities are endless. What custom functionality will you add to your HLK-7628?

Try this tutorial for yourself and share your experience in the comments below. I'd love to hear about the custom tools or features you're creating for your own router!