golang is unavailable for arm64

The gc compiler (http://golang.org/) does not support arm64

Dave, I understand that it currently doesn't have a first-class build, but after looking at the Go discussion forums it appears that there will be an arm64 build in the future,

https://groups.google.com/forum/#!searchin/golang-dev/arm64/golang-dev/A2SDyaNxDxs/zugPL5yDBwIJ
https://groups.google.com/forum/#!searchin/golang-dev/arm64/golang-dev/MLaz62sHUc0/0t6M2lx1imoJ

It looks like there are first-class builds for armv5 and armv7 for Linux on the Go build dashboard, and I would assume as more 64-bit ARM SBSA hardware makes it's way into the market place in the coming months we'll see more demand for architecture support.

Looking at some other go packages it appears they already have arm64 support as well, such as gccgo that you commented on in the golang-devel forums and Canonical contributing support for.

I understand that there isn't an official port yet, but marking as triaged or incomplete I believe is a better category for this since eventually when Go does offer arm64 as an arch the packages will need to be updated to support it.

With the docker.io package depending on golang, and the large uptake of container technology, having this package working on arm64 could open up many possibility for the new architecture in hyperscale environments.

If there is a better way to improve go support for arm64, specifically to enable Docker support, I am interested in hearing about that as well.

Michael

Some work has been done using gccgo to enable architectures that the golang gc complier does not support - however with docker, there will also be enablement work in Docker itself to make it function with anything other than amd64.

docker.io is now built on arm64 for 15.04

I'm actually really concerned by this change (speaking as both a Debian maintainer on the package, and as the maintainer of the build scripts upstream). We're actively working upstream on getting proper first-class gccgo compilation support into Docker's build system (https://github.com/docker/docker/issues/9207 for the tracker upstream), but one of the things we've noticed is that just because it doesn't FTBFS doesn't mean it actually works. Have you run it against the upstream integration tests to at least get an initial verification that the daemon works as expected?

Even the current patch headers are misleading:

> Description: Add gccgo build support for Power
> This patch is based on one that has been accepted upstream
> in trunk with some minor additions to deal with the way
> that the dh-golang helper works in Debian/Ubuntu.
> Origin: https://github.com/docker/docker/pull/10665

The "Description" claims this patch is actually based on something that exists upstream, but nothing like that patch exists upstream, and the "Origin" linked is a very different patch (and was merged as part of the work towards getting GCCGO upstream).

The current patch seems like it comes more from https://github.com/docker/docker/pull/10569 than from the referenced https://github.com/docker/docker/pull/10665, and basically this same diff has been rejected upstream multiple times.