Build Go for Newifi 2 (D1) router

This post will give you a guide to build Go on no matter which system.
Chinese Version

Prerequisite

1. After Go 1.5, all the source codes are written in Go or Assembly. So in a system where there is a Go install, we can build another Go using Go itself. The feature is called bootstrapping.
2. With GOOS and GOARCH flag, we can build Go program for given platform with given architecture. This is cross compile of Go.

So, it’s possible to build a Go environment for my Lenovo Newifi 2 (D1), which is based on OpenWRT, equiped with MIPS Little Endian MT7621AT processor, 256MB memory.

But I want to keep the official firmware, so I decided to build an independant build of Go for my router.

Preparing

Get your Go>=1.5 installed in your system:

> which go
/usr/bin/go
> go version
go version go1.10.4 linux/amd64

If you don’t have Go installed, please install it with your current package manager.
For Ubuntu,

> sudo apt-get install golang-go

Get Golang source code from the downloads page.

I chose to use Golang 1.12.4:

> wget https://dl.google.com/go/go1.12.4.src.tar.gz

Building

Decompress the tarball:

> tar xvf go1.12.4.src.tar.gz

We’ll have a directory like this:

.
├── api
├── AUTHORS
├── CONTRIBUTING.md
├── CONTRIBUTORS
├── doc
├── favicon.ico
├── lib
├── LICENSE
├── misc
├── PATENTS
├── README.md
├── robots.txt
├── src
├── test
└── VERSION

Enter src directory.
Begin directly your build for mipsle:

> GOOS=linux GOARCH=mipsle GOROOT_BOOTSTRAP=<your-go-root> ./make.bash
Building Go cmd/dist using <your-go-path>/go-1.10.
Building Go toolchain1 using <your-go-path>/go-1.10.
Building Go bootstrap cmd/go (go_bootstrap) using Go toolchain1.
Building Go toolchain2 using go_bootstrap and Go toolchain1.
Building Go toolchain3 using go_bootstrap and Go toolchain2.
Building packages and commands for host, linux/amd64.
Building packages and commands for target, linux/mipsle.
---
Installed Go for linux/mipsle in <your-build-path>/go
Installed commands in <your-build-path>/go/bin

Installing

After the building, copy the following folders to the router:

api   
bin   
misc  
pkg   
src   
test

For example, I created /mnt/mmcblk0p1/usr/share/go folder for them.

Then move go and gofmt from bin/mipsle to bin.

Add GOROOT to environment variables and bin to PATH:

> export GOROOT=/mnt/mmcblk0p1/usr/share/go
> PATH=$GOROOT/bin:$PATH

Run your first Go program

Create the Hello World code in test.go:

package main
import (
        "fmt"
)

func main() {
       fmt.Println("hello newifi2")
}

Run it:

> go run test.go
hello newifi2

or build and run it:

> go build test.go
> ./test
hello newifi2

Enjoy your journal with Go on your router!