ARM architecture support

[ferrouswheel]

I'm investigating ARM support, so that snetd can be run on low-powered devices like the Raspberry Pi and be used in IoT applications.

This issue is an attempt to log my progress.

Initially I'm trying to cross compile with the following:

env GOOS=linux GOARCH=arm GOARM=6 go build -o build/snetd-linux-arm6 snetd/main.go

The first issue is:

# github.com/singnet/snet-daemon/ratelimit
ratelimit/rateLimit.go:15:13: constant 9223372036854775807 overflows int

That can be fixed by using math.MaxInt32 instead of math.MaxInt64.

The next issue is that ethereum-go has to do some C compilation and requires xgo for cross-compilation to work properly.

build constraints exclude all Go files in /home/joel/go/src/github.com/singnet/snet-daemon/vendor/github.com/ethereum/go-ethereum/crypto/secp256k1

While cross compilation would make development faster and more convenient, tomorrow I'll try compiling directly on the Pi.

[vsbogd]

Looks like we need cross compilation in any case, for example to release Mac OS X binary, so solving cross compilation issue will be fruitful for daemon.

[ferrouswheel]

Update on this.

• the max message size is too large to fit in an int on arm, so I changed maxsizeOpt := grpc.MaxRecvMsgSize(math.MaxInt32)
• The RaspberryPi I'm working with doesn't have enough memory to compile the daemon (it has ~500MB) even if I set GOMAXPROCS=1

So looks like we will have to figure out cross-compilation.

[ferrouswheel]

Yes! Managed to snetd running on Raspberry Pi using xgo. I'll try to reproduce the steps, and make a PR with documentation.