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Omega Onion 2 + Go 1.8 = <3

Recent (or upcoming release) of Go 1.8 brings a lot features like SO plugins and major improvements. But i'm so hyped by hearing that GO 1.8 now supports MIPS32LE cross compiling!

Before Go 1.8

I'd like to say just a few words: gccgo from sources, custom OpenWRT builds with gccgo toolchains IMHO, too much problems with such small devices like IoT thing.

With Go 1.8

With new cross-compiling features of Go 1.8rc3 i was able build a Gorilla Mux web server and run it successfully on Onion Omega 2

Here's what you need

$ export GOPATH=~/go
$ go get -u github.com/gorilla/mux

In order to build our simple http server you need to use following command:

$ GOOS=linux GOARCH=mipsle go build -compiler gc mux_server.go

Note the cross-compilation options: GOOS=linux GOARCH=mipsle that aim for linux and MIPS Little Endian (Omega 2's architecture).

Boom! Now you have executable binary app, copy it over WiFi to you Omega2

$ scp mux_server root@192.168.3.1:/root

Take a look at Omega 2 Getting started guide for more information how to connect to your device.

Here's an example for Hello World app:

BusyBox v1.25.1 () built-in shell (ash)

   ____       _             ____
  / __ \___  (_)__  ___    / __ \__ _  ___ ___ ____ _
 / /_/ / _ \/ / _ \/ _ \  / /_/ /  ' \/ -_) _ `/ _ `/
 \____/_//_/_/\___/_//_/  \____/_/_/_/\__/\_, /\_,_/
 W H A T  W I L L  Y O U  I N V E N T ? /___/
 -----------------------------------------------------
   Ω-ware: 0.1.9 b149
 -----------------------------------------------------
root@IronOmega:~# ls -la
drwxr-xr-x    1 root     root           0 Feb  5 21:07 .
drwxr-xr-x    1 root     root           0 Feb  5 20:02 ..
-rwxr-xr-x    1 root     root        3.7M Feb  5 21:08 mux_server
-rwxr-xr-x    1 root     root        1.0M Feb  5 22:20 hello_world

root@IronOmega:~# ./hello_world 
Hello linux/mipsle

Negative effect

mux_server file with 25 LOC has size of 539 bytes, but its binary file weights something around 5.5Mb. Onion Omega 2 chip comes with 14Mb storage available, so there's no so much space for a good party, unfortunately.

Positive effect

Thanks to quite impressive Go capabilities to shrink its binaries and make them more affordable for IoT devices with limited storage.

$ GOOS=linux GOARCH=mipsle go build -ldflags "-s -w" -compiler gc mux_server.go

Boom! And your binary gets lighter up to 2Mb (almost half size of initial).

Conclusions

Go 1.8 made great progress in its cross-compiling features along with capability to shrink compiled binaries into affordable size. Go made a good step forward into IoT world as de-facto standard development language for MIPS32 devices.